w3schools.com
Free website and domain report on w3schools.com
Last Updated: 22nd September, 2024
Overview
Snoop Summary for w3schools.com
This is a free and comprehensive report about w3schools.com. The domain w3schools.com is currently hosted on a server located in United States with the IP address 13.248.240.135, where the local currency is USD and English is the local language. Our records indicate that w3schools.com is owned/operated by Identity Protection Service. W3schools.com is expected to earn an estimated $260,867 USD per day from advertising revenue. The sale of w3schools.com would possibly be worth $190,432,986 USD. This figure is based on the daily revenue potential of the website over a 24 month period. W3schools.com is unbelievably popular with an estimated 18,881,967 daily unique visitors. This report was last updated 22nd September, 2024.
About w3schools.com
| Site Preview: |   |
| Title: | W3Schools Online Web Tutorials |
| Description: | |
| Keywords and Tags: | ajax, ascii, background image, c, color, css, font style, html table, javascript, li, popular, python dictionary, python for loop, python if else, sql join, technical information, w3schools |
| Related Terms: | w3schools sql |
| Fav Icon: | |
| Age: | Over 24 years old |
| Domain Created: | 21st March, 2000 |
| Domain Updated: | 7th January, 2023 |
| Domain Expires: | 21st March, 2026 |
Review
Snoop Score
5/5 (Perfect!)
Valuation
$190,432,986 USD
Note: All valuation figures are estimates.
Popularity
Worldwide Sensation
Note: Popularity is estimated.
Rank, Reach and Authority
| Alexa Rank: | 120 |
| Alexa Reach: | |
| SEMrush Rank (US): | 414 |
| SEMrush Authority Score: | 80 |
| Moz Domain Authority: | 0 |
| Moz Page Authority: | 0 |
Organic vs Paid (Google Ads)
| Organic | Paid | |
|---|---|---|
| Keywords: | 591,828 | 0 |
| Traffic: | 8,414,744 | 0 |
| Cost: | $8,040,924 USD | $0 USD |
Traffic
Visitors
| Daily Visitors: | 18,881,967 |
| Monthly Visitors: | 574,707,595 |
| Yearly Visitors: | 6,891,917,955 |
Note: All visitors figures are estimates.
Visitors By Country
Revenue
Revenue
| Daily Revenue: | $260,867 USD |
| Monthly Revenue: | $7,939,972 USD |
| Yearly Revenue: | $95,216,488 USD |
Note: All revenue figures are estimates.
Revenue By Country
SEO
Backlinks Analysis (SEMrush)
| Backlinks: | 38,198,836 |
| Referring Domains: | 117,543 |
| Referring IPs: | 100,345 |
W3schools.com has 38,198,836 backlinks according to SEMrush. 91% of these backlinks are "dofollow" (follow) links which allow the flow of link equity to pass through, which may improve w3schools.com's search engine rankings. Other links are treated as 'hints' by search engines and may also pass link equity, depending on what search engines decide in each case.
100% of w3schools.com's backlinks are text and image links, which are ideal for SEO. Other backlink types may be unrecognized or ignored by search engines.
Top New Follow Links
1
Source: http://www.iaitew.me/
Target: https://www.w3schools.com/whatis/img_http.jpg
2
Source: https://www.globos.nl/ballonshop/
Target: https://www.w3schools.com/w3css/default.asp
3
Source: http://canadiancialisytq.com/
Target: https://www.w3schools.com/
4
Source: https://bulgariatravel.org/
Target: https://www.w3schools.com/
5
Source: http://homeairconditioningoutlet.com/product/generic-cialis/
Target: http://www.w3schools.com/
Top Ranking Keywords (US)
1
Keyword: ajax
Ranked Page: https://www.w3schools.com/xml/ajax_intro.asp
2
Keyword: w3schools
Ranked Page: https://www.w3schools.com/
3
Keyword: li
Ranked Page: https://www.w3schools.com/tags/tag_li.asp
4
Keyword: css
Ranked Page: https://www.w3schools.com/css/
5
Keyword: color
Ranked Page: https://www.w3schools.com/colors/colors_picker.asp?color=009E73
Domain Analysis
| Value | Length | |
|---|---|---|
| Domain: | w3schools.com | 13 |
| Domain Name: | w3schools | 9 |
| Extension (TLD): | com | 3 |
| Expiry Check: | |
Page Speed Analysis
| Average Load Time: | 0.85 seconds |
| Load Time Comparison: | Faster than 80% of sites |
PageSpeed Insights
Avg. (All Categories)
Performance
Accessibility
Best Practices
SEO
PWA
0–49 (Fail) 50–89 (Average) 90–100 (Pass) 
URL: https://www.w3schools.com/
Updated: 21st October, 2022
0.80 seconds
First Contentful Paint (FCP)
0.00 seconds
First Input Delay (FID) Simulate loading on desktop
Performance
Indicates how well the page is performing and highlights opportunities where performance may be improved for w3schools.com. This includes details about optimizing page load times which can result in a better user experience.Metrics
First Contentful Paint — 0.7 s The time taken for the first image or text on the page to be rendered.
Time to Interactive — 1.8 s The time taken for the page to become fully interactive.
Speed Index — 0.7 s The time taken for the page contents to be visibly populated.
Largest Contentful Paint — 1.0 s The timing of the largest text or image that is painted.
Cumulative Layout Shift — 0 Cumulative Layout Shift is the measurement of visible elements collective movement within the viewport.
View Data
Audits
First Meaningful Paint — 0.7 s The time taken for the primary content of the page to be rendered.
Network Requests Below is a list of network requests that were made during page load.
| URL | Protocol | Start Time (Ms) | End Time (Ms) | Transfer Size (Bytes) | Resource Size (Bytes) | Status Code | MIME Type | Resource Type |
|---|---|---|---|---|---|---|---|---|
| http://w3schools.com/ | http/1.1 | 0 | 161.25000000466 | 268 | 0 | 301 | text/html | |
| https://www.w3schools.com/ | h2 | 161.61399998236 | 180.10799994227 | 115925 | 115349 | 200 | text/html | Document |
| https://www.w3schools.com/lib/fonts/fontawesome.woff2?14663396 | h2 | 188.41099995188 | 192.4299999373 | 10664 | 10176 | 200 | application/font-woff2 | Font |
| https://www.w3schools.com/lib/fonts/source-code-pro-v14-latin-regular.woff2 | h2 | 188.58600000385 | 199.14099993184 | 14251 | 13764 | 200 | application/font-woff2 | Font |
| https://www.w3schools.com/lib/fonts/roboto-mono-v13-latin-500.woff2 | h2 | 188.77299991436 | 201.4059999492 | 12975 | 12488 | 200 | application/font-woff2 | Font |
| https://www.w3schools.com/lib/fonts/source-sans-pro-v14-latin-700.woff2 | h2 | 189.03100001626 | 198.84999992792 | 16251 | 15764 | 200 | application/font-woff2 | Font |
| https://www.w3schools.com/lib/fonts/source-sans-pro-v14-latin-600.woff2 | h2 | 189.26899996586 | 199.77800000925 | 16435 | 15948 | 200 | application/font-woff2 | Font |
| https://www.w3schools.com/lib/fonts/freckle-face-v9-latin-regular.woff2 | h2 | 189.412000007 | 200.38099994417 | 40139 | 39652 | 200 | application/font-woff2 | Font |
| https://www.w3schools.com/lib/w3schools30.css | h2 | 189.60799998604 | 261.32299995515 | 13182 | 63308 | 200 | text/css | Stylesheet |
| https://cdn.snigelweb.com/adengine/w3schools.com/loader.js | h2 | 263.1490000058 | 361.58399994019 | 7058 | 15692 | 200 | application/javascript | Script |
| https://www.w3schools.com/lib/common-deps.js?v=1.0.0 | h2 | 190.13799994718 | 201.11799996812 | 1833 | 2807 | 200 | application/javascript | Script |
| https://www.w3schools.com/lib/user-session.js?v=1.0.2 | h2 | 190.32599998172 | 202.0720000146 | 2692 | 8922 | 200 | application/javascript | Script |
| https://www.w3schools.com/lib/my-learning.js?v=1.0.11 | h2 | 190.55699999444 | 198.12299998011 | 4920 | 18640 | 200 | application/javascript | Script |
| https://www.w3schools.com/lib/uic.js?v=1.0.5 | h2 | 190.83099998534 | 260.45399997383 | 25638 | 70334 | 200 | application/javascript | Script |
| https://www.w3schools.com/lib/w3codecolor.js | h2 | 190.98999991547 | 197.75299995672 | 7315 | 31504 | 200 | application/javascript | Script |
| https://www.googletagmanager.com/gtm.js?id=GTM-KTCFC3S | h2 | 268.58699996956 | 290.54099996574 | 48779 | 126179 | 200 | application/javascript | Script |
| https://www.w3schools.com/howto/tryhow_js_slideshow_ifr.htm | h2 | 362.2210000176 | 366.67599994689 | 1813 | 3516 | 200 | text/html | Document |
| https://www.w3schools.com/spaces/files/priscilla-du-preez-XkKCui44iM0-unsplash.921aa0c0.jpg | h2 | 386.3559999736 | 398.13899993896 | 331731 | 331235 | 200 | image/jpeg | Image |
| https://www.w3schools.com/about/w3codes.png | h2 | 386.75900001545 | 555.96599995624 | 18305 | 17831 | 200 | image/png | Image |
| https://www.w3schools.com/howto/img_nature_wide.jpg | h2 | 583.36799999233 | 590.83000000101 | 52326 | 51851 | 200 | image/jpeg | Image |
| https://www.w3schools.com/howto/img_snow_wide.jpg | h2 | 583.52300000843 | 590.00299999025 | 33735 | 33260 | 200 | image/jpeg | Image |
| https://www.w3schools.com/howto/img_mountains_wide.jpg | h2 | 602.57599991746 | 660.50300002098 | 60880 | 60405 | 200 | image/jpeg | Image |
| https://www.google-analytics.com/analytics.js | h2 | 599.54199998174 | 604.11700000986 | 20664 | 50230 | 200 | text/javascript | Script |
| https://cdn.snigelweb.com/prebid/7.17.0/prebid.js?v=4950-1666165383718 | h2 | 680.84499996621 | 762.3939999612 | 158655 | 556444 | 200 | application/javascript | Script |
| https://c.amazon-adsystem.com/aax2/apstag.js | h2 | 681.42999999691 | 689.32999996468 | 45047 | 180832 | 200 | application/javascript | Script |
| https://securepubads.g.doubleclick.net/tag/js/gpt.js | h2 | 681.72200000845 | 687.51099996734 | 28211 | 80700 | 200 | text/javascript | Script |
| https://adengine.snigelweb.com/w3schools.com/4950-1666165383718/adngin.js | h2 | 681.9559999276 | 761.10000000335 | 387 | 133 | 200 | application/javascript | Script |
| https://cdn.snigelweb.com/argus/argus.js | h2 | 682.4899999192 | 760.60599996708 | 12444 | 36911 | 200 | application/javascript | Script |
| https://www.google-analytics.com/j/collect?v=1&_v=j98&a=1351753448&t=pageview&_s=1&dl=https%3A%2F%2Fwww.w3schools.com%2F&ul=en-us&de=UTF-8&dt=W3Schools%20Online%20Web%20Tutorials&sd=24-bit&sr=800x600&vp=1350x940&je=0&_u=YEBAAEABAAAAACAAI~&jid=1901515557&gjid=564391681&cid=426295865.1666370113&tid=UA-3855518-1&_gid=1031364653.1666370113&_r=1>m=2wgaj0KTCFC3S&z=1847295961 | h2 | 791.99199995492 | 795.64399993978 | 616 | 2 | 200 | text/plain | XHR |
| https://stats.g.doubleclick.net/j/collect?t=dc&aip=1&_r=3&v=1&_v=j98&tid=UA-3855518-1&cid=426295865.1666370113&jid=1901515557&gjid=564391681&_gid=1031364653.1666370113&_u=YEBAAEAAAAAAACAAI~&z=1739916398 | h2 | 873.07500001043 | 876.78900000174 | 689 | 2 | 200 | text/plain | XHR |
| https://securepubads.g.doubleclick.net/gpt/pubads_impl_2022101801.js | h2 | 891.99499995448 | 902.44699991308 | 131684 | 387895 | 200 | text/javascript | Script |
| https://securepubads.g.doubleclick.net/pagead/ppub_config?ippd=www.w3schools.com | h2 | 893.25700001791 | 898.32999999635 | 1400 | 1631 | 200 | application/json | XHR |
| https://c.amazon-adsystem.com/bao-csm/aps-comm/aps_csm.js | h2 | 907.30600000825 | 911.18099994492 | 3272 | 6482 | 200 | application/javascript | XHR |
| https://www.google.com/ads/ga-audiences?t=sr&aip=1&_r=4&slf_rd=1&v=1&_v=j98&tid=UA-3855518-1&cid=426295865.1666370113&jid=1901515557&_u=YEBAAEAAAAAAACAAI~&z=601191883 | h2 | 1075.9899999248 | 1083.9729999425 | 673 | 42 | 200 | image/gif | Image |
Network Round Trip Times — 0 ms High Network RTT (Round Trip Times) can have a large impact on performance. Providing servers geographically closer to the user could improve performance.
Server Backend Latencies — 0 ms High server latencies indicate the server is overloaded or has a poor backend performance.
Tasks Below is a list of the top-level main thread tasks that executed during page load.
| Start Time (Ms) | End Time (Ms) |
|---|---|
| 184.024 | 13.425 |
| 268.078 | 6.492 |
| 274.582 | 16.747 |
| 296.397 | 84.479 |
| 382.456 | 184.156 |
| 566.924 | 10.999 |
| 577.935 | 6.796 |
| 589.237 | 12.809 |
| 604.759 | 78.406 |
| 685.327 | 79.589 |
| 774.044 | 19.225 |
| 793.305 | 72.606 |
| 874.138 | 20.491 |
| 894.681 | 13.988 |
| 908.725 | 165.747 |
| 1104.72 | 116.278 |
Script Treemap Data Provide as required, for treemap app.
Other
Eliminate render-blocking resources Resources, such as JavaScript and style sheets, can block the first paint of the page. W3schools.com should consider delivering critical JavaScript/style sheets (JS/CSS) inline and deferring all non-critical JS/CSS.
Properly size images Images can slow down the page's load time. W3schools.com should consider serving more appropriate-sized images.
Defer offscreen images — Potential savings of 323 KiB Time to Interactive can be slowed down by resources on the page. W3schools.com should consider lazy-loading offscreen and hidden images.
| URL | Resource Size (Bytes) | Potential Savings (Bytes) |
|---|---|---|
| https://www.w3schools.com/spaces/files/priscilla-du-preez-XkKCui44iM0-unsplash.921aa0c0.jpg | 331235 | 331235 |
Minify CSS — Potential savings of 3 KiB Cascading Style Sheets (CSS) files can contribute to network payload sizes. W3schools.com should consider minifying CSS files.
| URL | Transfer Size (Bytes) | Potential Savings (Bytes) |
|---|---|---|
| /* Customize w3schools23.css */
#nav_tutorials,
#nav_references,
#nav_exercises {
margin-top: 0;
} ... | 13307 | 2584 |
Minify JavaScript — Potential savings of 2 KiB JavaScript (JS) files can contribute to network payload sizes and increase script parse times. W3schools.com should consider minifying JS files.
| URL | Transfer Size (Bytes) | Potential Savings (Bytes) |
|---|---|---|
| inline:
MyLearning.loadUser('default');
w3Co... | 15126 | 2393 |
Reduce unused CSS — Potential savings of 11 KiB Dead and/or unused rules in Style Sheets (CSS) can contribute to network payload sizes. W3schools.com should consider removing dead rules from style sheets and deferring the loading of CSS not used for above-the-fold content.
| URL | Transfer Size (Bytes) | Potential Savings (Bytes) |
|---|---|---|
| https://www.w3schools.com/lib/w3schools30.css | 13182 | 11751 |
Efficiently encode images Unoptimized images can consume more cellular data than what is necessary.
Serve images in next-gen formats — Potential savings of 206 KiB Consider JPEG 2000, JPEG XR or WebP image formats which provide better compression than PNG and JPEG.
| URL | Resource Size (Bytes) | Potential Savings (Bytes) |
|---|---|---|
| https://www.w3schools.com/spaces/files/priscilla-du-preez-XkKCui44iM0-unsplash.921aa0c0.jpg | 331235 | 163704.8 |
| https://www.w3schools.com/howto/img_mountains_wide.jpg | 60405 | 19593.85 |
| https://www.w3schools.com/howto/img_nature_wide.jpg | 51851 | 18195.6 |
| https://www.w3schools.com/about/w3codes.png | 17831 | 9367.8 |
Enable text compression Text-based resources should be served with compression, such as gzip, deflate or brotli.
Preconnect to required origins Resource hints, such as 'preconnect' or 'dns-prefetch', may assist in establishing early connections to important third-party origins.
Initial server response time was short — Root document took 20 ms It is advised to keep the server response time short for the main document, because all other requests depend on it.
| URL | Time Spent (Ms) |
|---|---|
| https://www.w3schools.com/ | 19.49 |
Avoid multiple page redirects — Potential savings of 190 ms Redirects can cause additional delays before the page can begin loading. W3schools.com should avoid multiple or unnecessary page redirects.
| URL | Time Spent (Ms) |
|---|---|
| http://w3schools.com/ | 190 |
| https://www.w3schools.com/ | 0 |
Preload key requests Key requests can be preloaded by using '<link rel=preload>'. W3schools.com should consider using '<link rel=preload>' to prioritize fetching resources that are currently requested later in page load.
Use video formats for animated content Large GIFs are inefficient for delivering animated content. It is recommended to use MPEG4/WebM videos for animations and PNG/WebP for static images instead of GIF.
Remove duplicate modules in JavaScript bundles Ensure that no duplicate JavaScript modules from bundles exist to reduce bytes consumed by network activity.
Avoid serving legacy JavaScript to modern browsers — Potential savings of 0 KiB Polyfills and transforms enable legacy browsers to use new JavaScript features. For bundled JavaScript it is recommended to adopt a modern script deployment strategy using module/nomodule feature detection. This will reduce the amount of code shipped to modern browsers.
| URL | Potential Savings (Bytes) |
|---|---|
| https://c.amazon-adsystem.com/aax2/apstag.js | 109 |
| https://cdn.snigelweb.com/prebid/7.17.0/prebid.js?v=4950-1666165383718 | 48 |
Preload Largest Contentful Paint image It is recommended to preload images used by LCP elements, to improve LCP time.
Avoids enormous network payloads — Total size was 1,212 KiB Large network payloads can cost users money and are linked to long load times.
| URL | Transfer Size (Bytes) |
|---|---|
| https://www.w3schools.com/spaces/files/priscilla-du-preez-XkKCui44iM0-unsplash.921aa0c0.jpg | 331731 |
| https://cdn.snigelweb.com/prebid/7.17.0/prebid.js?v=4950-1666165383718 | 158655 |
| https://securepubads.g.doubleclick.net/gpt/pubads_impl_2022101801.js | 131684 |
| https://www.w3schools.com/ | 115925 |
| https://www.w3schools.com/howto/img_mountains_wide.jpg | 60880 |
| https://www.w3schools.com/howto/img_nature_wide.jpg | 52326 |
| https://www.googletagmanager.com/gtm.js?id=GTM-KTCFC3S | 48779 |
| https://c.amazon-adsystem.com/aax2/apstag.js | 45047 |
| https://www.w3schools.com/lib/fonts/freckle-face-v9-latin-regular.woff2 | 40139 |
| https://www.w3schools.com/howto/img_snow_wide.jpg | 33735 |
Avoid chaining critical requests — 6 chains found Below is a list of Critical Request Chains, which shows which resources are loaded with a high priority. W3schools.com should consider reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load.
User Timing marks and measures — 6 user timings Make use of the User Timing API to measure an app's real-world performance during key user experiences.
| Name | Type | Start Time (Ms) | Duration (Ms) |
|---|---|---|---|
| lteu | Measure | 1080.757 | 0.148 |
| ltpq | Measure | 1080.984 | 0.03 |
| loadStarteventUtils | Mark | 1080.795 | |
| loadEndeventUtils | Mark | 1080.91 | |
| loadStartpixelQueue | Mark | 1080.988 | |
| loadEndpixelQueue | Mark | 1081.018 |
JavaScript execution time — 0.5 s JavaScript (JS) execution time can be lowered by reducing the time required for parsing, compiling and executing JS. Delivering smaller JS payloads may help with this.
| URL | Total CPU Time (Ms) | Script Evaluation (Ms) | Script Parse (Ms) |
|---|---|---|---|
| https://www.w3schools.com/ | 309.218 | 15.084 | 3.493 |
| https://cdn.snigelweb.com/prebid/7.17.0/prebid.js?v=4950-1666165383718 | 165.446 | 112.665 | 52.641 |
| https://securepubads.g.doubleclick.net/gpt/pubads_impl_2022101801.js | 116.54 | 56.641 | 59.68 |
| https://www.w3schools.com/howto/tryhow_js_slideshow_ifr.htm | 94.68 | 1.741 | 1.123 |
| https://cdn.snigelweb.com/adengine/w3schools.com/loader.js | 80.201 | 75.961 | 3.108 |
| https://cdn.snigelweb.com/argus/argus.js | 72.276 | 71.505 | 0.617 |
Minimizes main-thread work — 1.0 s Main-thread work timing can be lowered by reducing the time required for parsing, compiling and executing JS. Delivering smaller JS payloads may help with this.
| Category | Time Spent (Ms) |
|---|---|
| Script Evaluation | 413.014 |
| Style & Layout | 268.879 |
| Script Parsing & Compilation | 132.953 |
| Parse HTML & CSS | 80.317 |
| Other | 65.624 |
| Rendering | 16.874 |
All text remains visible during webfont loads Make use of the font-display CSS feature, which will ensure text is user-visible while webfonts are loading.
Keep request counts low and transfer sizes small — 34 requests • 1,212 KiB It is advised to add a budgets.json file in order to set budgets for the quantity and size of page resources.
| Resource Type | Requests | Transfer Size (Bytes) |
|---|---|---|
| Total | 34 | 1240857 |
| Image | 6 | 497650 |
| Script | 14 | 495327 |
| Document | 2 | 117738 |
| Font | 6 | 110715 |
| Stylesheet | 1 | 13182 |
| Other | 5 | 6245 |
| Media | 0 | 0 |
| Third-party | 14 | 459579 |
Minimize third-party usage — Third-party code blocked the main thread for 10 ms It is advised to either limit, remove or delay the loading of redundant third-party code which may be significantly impacting load performance.
| Third-Party | Transfer Size (Bytes) | Main-Thread Blocking Time (Ms) |
|---|---|---|
| 161984 | 11.174 | |
| 48779 | 0 | |
| 48319 | 0 | |
| 21280 | 0 | |
| 673 | 0 |
Lazy load third-party resources with facades Consider replacing third-party embeds with a facade until they are required (use lazy loading).
Largest Contentful Paint element — 1 element found The element which was identified as the Largest Contentful Paint.
| Element |
|---|
Largest Contentful Paint image was not lazily loaded Above-the-fold images that are lazily loaded render later in the page lifecycle, which can delay the largest contentful paint.
Avoid large layout shifts Below is a list of all DOM elements that contribute to the CLS of the page.
Uses passive listeners to improve scrolling performance Improve the page's scroll performance by marking touch and wheel event listeners as 'passive'.
Avoids `document.write()` Avoid or limit the use of external scripts that are dynamically injected via 'document.write()' as users on slow connections will be delayed by tens of seconds.
Avoid long main-thread tasks — 5 long tasks found Below is a list of the longest tasks on the main thread, which is useful when identifying the worst input delay contributors.
| URL | Start Time (Ms) | Duration (Ms) |
|---|---|---|
| https://cdn.snigelweb.com/prebid/7.17.0/prebid.js?v=4950-1666165383718 | 1502 | 166 |
| https://securepubads.g.doubleclick.net/gpt/pubads_impl_2022101801.js | 1760 | 116 |
| https://www.w3schools.com/ | 561 | 92 |
| https://www.w3schools.com/lib/uic.js?v=1.0.5 | 980 | 84 |
| https://cdn.snigelweb.com/argus/argus.js | 1687 | 73 |
Avoid non-composited animations It is recommended to avoid non-composited animations which are often janky and increase CLS.
Has a `<meta name="viewport">` tag with `width` or `initial-scale` It is advised to use a '<meta name="viewport">' tag for the optimization of w3schools.com on mobile screens.
Avoids `unload` event listeners The 'unload' event does not fire reliably, causing issues with browser optimizations such as the Back-Forward Cache. It is recommended that 'pagehide' or 'visibilitychange' events are used instead.
Budgets
Performance budget It is advised to keep the quantity and size of all network requests under the targets set by the provided performance budget.
Timing budget It is advised to set a timing budget to monitor the performance of your site.
Metrics
Total Blocking Time — 210 ms The total blocking time is the sum of all time periods between First Contentful Paint and Time to Interactive (when task length exceeded 50ms).
Audits
Max Potential First Input Delay — 170 ms Users could experience a delay when interacting with the page.
Other
Reduce unused JavaScript — Potential savings of 310 KiB It is advised to remove unused JavaScript in order to reduce bytes consumed by network activity.
| URL | Transfer Size (Bytes) | Potential Savings (Bytes) |
|---|---|---|
| https://cdn.snigelweb.com/prebid/7.17.0/prebid.js?v=4950-1666165383718 | 158655 | 134608 |
| https://securepubads.g.doubleclick.net/gpt/pubads_impl_2022101801.js | 131684 | 100270 |
| https://c.amazon-adsystem.com/aax2/apstag.js | 45047 | 34411 |
| https://www.googletagmanager.com/gtm.js?id=GTM-KTCFC3S | 48779 | 24252 |
| https://www.w3schools.com/lib/uic.js?v=1.0.5 | 25638 | 23731 |
Avoid an excessive DOM size — 939 elements A large DOM (Document Object Model) will increase memory usage, cause longer system calculations as well as costly layout reflows.
| Statistic | Element | Value |
|---|---|---|
| Total DOM Elements | 939 | |
| Maximum DOM Depth | 11 | |
| Maximum Child Elements | 38 |
Other
Serve static assets with an efficient cache policy — 19 resources found W3schools.com can speed up repeat visits by increasing the cache lifetime, which is essentially how long before a cached copy expires.
| URL | Cache TTL (Ms) | Transfer Size (Bytes) |
|---|---|---|
| https://c.amazon-adsystem.com/aax2/apstag.js | 3600000 | 45047 |
| https://www.google-analytics.com/analytics.js | 7200000 | 20664 |
| https://www.w3schools.com/spaces/files/priscilla-du-preez-XkKCui44iM0-unsplash.921aa0c0.jpg | 14400000 | 331731 |
| https://www.w3schools.com/howto/img_mountains_wide.jpg | 14400000 | 60880 |
| https://www.w3schools.com/howto/img_nature_wide.jpg | 14400000 | 52326 |
| https://www.w3schools.com/lib/fonts/freckle-face-v9-latin-regular.woff2 | 14400000 | 40139 |
| https://www.w3schools.com/howto/img_snow_wide.jpg | 14400000 | 33735 |
| https://www.w3schools.com/lib/uic.js?v=1.0.5 | 14400000 | 25638 |
| https://www.w3schools.com/about/w3codes.png | 14400000 | 18305 |
| https://www.w3schools.com/lib/fonts/source-sans-pro-v14-latin-600.woff2 | 14400000 | 16435 |
| https://www.w3schools.com/lib/fonts/source-sans-pro-v14-latin-700.woff2 | 14400000 | 16251 |
| https://www.w3schools.com/lib/fonts/source-code-pro-v14-latin-regular.woff2 | 14400000 | 14251 |
| https://www.w3schools.com/lib/w3schools30.css | 14400000 | 13182 |
| https://www.w3schools.com/lib/fonts/roboto-mono-v13-latin-500.woff2 | 14400000 | 12975 |
| https://www.w3schools.com/lib/fonts/fontawesome.woff2?14663396 | 14400000 | 10664 |
| https://www.w3schools.com/lib/w3codecolor.js | 14400000 | 7315 |
| https://www.w3schools.com/lib/my-learning.js?v=1.0.11 | 14400000 | 4920 |
| https://www.w3schools.com/lib/user-session.js?v=1.0.2 | 14400000 | 2692 |
| https://www.w3schools.com/lib/common-deps.js?v=1.0.0 | 14400000 | 1833 |
Image elements do not have explicit `width` and `height` Reduce layout shifts and improve CLS by setting explicit width and height properties on image elements.
| URL |
|---|
Accessibility
Indicates how accessible the page is and highlights opportunities where the page can be made more accessible to users of w3schools.com. This includes details about various page attributes that can be optimized.Navigation
`[accesskey]` values are unique Access keys assist users with focusing on different parts of the page. Each access key should be unique for proper navigation.
The page contains a heading, skip link, or landmark region It is advised to provide ways to bypass repetitive content, allowing users to navigate the page efficiently.
`[id]` attributes on active, focusable elements are unique Ensure all focusable elements have a unique id value to allow them to be visible to users of assistive technologies, like a screen reader.
No element has a `[tabindex]` value greater than 0 Although technically valid, a tabindex value greater than 0 often creates frustrating experiences for users who rely on assistive technologies.
ARIA
`[aria-*]` attributes match their roles Avoid mismatching 'aria-*' attributes and their 'role' value, as it invalidates the attribute.
`button`, `link`, and `menuitem` elements have accessible names Without accessible names on elements, screen readers will default to announcing a generic name, which means your content will be less accessible to users who rely on screen readers.
`[aria-hidden="true"]` is not present on the document `<body>` If aria-hidden=true is set on the document body, assistive technologies, like a screen reader will work inconsistently.
`[aria-hidden="true"]` elements do not contain focusable descendents Interactive elements within an aria-hidden=true element are unavailable to users of assistive technologies, like a screen reader.
ARIA input fields have accessible names Generic names are announced to users of assistive technologies, like a screen reader, when an input field does not have an accessible name specified.
ARIA `meter` elements have accessible names Without accessible names on elements, screen readers will default to announcing a generic name, which means your content will be less accessible to users who rely on screen readers.
ARIA `progressbar` elements have accessible names Without accessible names on elements, screen readers will default to announcing a generic name, which means your content will be less accessible to users who rely on screen readers.
`[role]`s have all required `[aria-*]` attributes Some ARIA roles have required 'aria-*' attributes, which provide essential information about state and functionality.
Elements with an ARIA `[role]` that require children to contain a specific `[role]` have all required children. Some ARIA parent roles cannot perform their intended functions if specific child roles are not used.
`[role]`s are contained by their required parent element Some ARIA child roles cannot perform their intended functions if specific parent roles are not used.
`[role]` values are valid All ARIA roles require valid values to perform their intended functions.
ARIA toggle fields have accessible names Generic names are announced to users of assistive technologies, like a screen reader, when a toggle field does not have an accessible name specified.
ARIA `tooltip` elements have accessible names Without accessible names on elements, screen readers will default to announcing a generic name, which means your content will be less accessible to users who rely on screen readers.
ARIA `treeitem` elements have accessible names Without accessible names on elements, screen readers will default to announcing a generic name, which means your content will be less accessible to users who rely on screen readers.
`[aria-*]` attributes have valid values ARIA attributes cannot be interpreted with invalid values when used by screen readers and other assistive technologies.
`[aria-*]` attributes are valid and not misspelled ARIA attributes cannot be interpreted with invalid names when used by screen readers and other assistive technologies.
ARIA IDs are unique Ensure all ARIA ID values are unique to prevent elements from being overlooked by assistive technologies, like a screen reader.
Tables and lists
`<dl>`'s contain only properly-ordered `<dt>` and `<dd>` groups, `<script>`, `<template>` or `<div>` elements. Screen readers and other assistive technologies may produce poor and inaccurate output when definition lists are not properly marked up.
Definition list items are wrapped in `<dl>` elements In order for screen readers and other assistive technologies to properly announce definition list items ('<dt>' and '<dd>'), they must be wrapped in parent a '<dl>' element.
Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`). Use proper list structure to aid screen readers and other assistive technologies.
List items (`<li>`) are contained within `<ul>` or `<ol>` parent elements In order for screen readers to announce list items, ensure that list items ('<li>') are contained within parent '<ul>' or '<ol>' tags.
Cells in a `<table>` element that use the `[headers]` attribute refer to table cells within the same table. Screen readers and other assistive technologies have features to make navigating tables easier. Ensure that '<td>' cells using the headers attribute only refer to other cells in the same table, to improve screen reader user experience.
`<th>` elements and elements with `[role="columnheader"/"rowheader"]` have data cells they describe. Screen readers and other assistive technologies have features to make navigating tables easier. Ensure that table headers refer to some set of cells, to improve screen reader user experience.
Names and labels
Document has a `<title>` element Search engines, screen reader users and other assistive technology users rely on the title to provide an overview of the page and to help determine if the page is relevant to their search.
No form fields have multiple labels Having multiple labels for form fields can be confusing to assistive technologies, like a screen reader.
`<input type="image">` elements have `[alt]` text Input buttons with alternative text assist screen readers and other assistive technology users to understand its purpose.
Links have a discernible name In order to improve the navigation for screen reader and other assistive technology users, use link text that is unique, focusable and discernible.
`<object>` elements have alternate text It is advised that alt text is used on '<object>' elements in order to provide meaning to screen reader and other assistive technology users, as these technologies are unable to translate non-text content.
Internationalization and localization
`<html>` element has a `[lang]` attribute It is advised to provide a lang attribute so that screen readers and other assistive technologies are guaranteed to announce the page's text correctly. When not provided, the user's default language setting will be used which may cause inaccuracies.
`<html>` element has a valid value for its `[lang]` attribute Specify a valid BCP 47 language in order to help screen readers and other assistive technologies announce text properly.
`[lang]` attributes have a valid value Specify a valid BCP 47 language on elements in order to help screen readers and other assistive technologies announce text properly.
Best practices
The document does not use `<meta http-equiv="refresh">` Pages that refresh automatically cause a poor user experience as focus is directed back to the top of the page unexpectedly.
`[user-scalable="no"]` is not used in the `<meta name="viewport">` element and the `[maximum-scale]` attribute is not less than 5. For users with low vision who rely on screen magnification, ensure that zooming is not disabled.
Audio and video
`<video>` elements contain a `<track>` element with `[kind="captions"]` W3schools.com may provide assistance to deaf or hearing-impaired users with captions on videos.
Names and labels
Buttons do not have an accessible name Buttons become unusable as they are announced simply as "button" when the button does not have an accessible name, when used by screen readers and other assistive technologies.
| Failing Elements |
|---|
`<frame>` or `<iframe>` elements do not have a title Screen reader users and other assistive technology users rely on frame titles to describe the contents of frames.
| Failing Elements |
|---|
Image elements do not have `[alt]` attributes Provide short and descriptive alternative text where possible on informative elements.
| Failing Elements |
|---|
Form elements do not have associated labels Screen readers and other assistive technologies rely on labels to properly announce form controls.
| Failing Elements |
|---|
Contrast
Background and foreground colors do not have a sufficient contrast ratio. Many (if not most) users find low-contrast text difficult or impossible to read.
| Failing Elements |
|---|
Navigation
Heading elements are not in a sequentially-descending order Properly order all headers and do not skip heading levels to better the navigation and readability for users of assistive technologies, like a screen reader.
| Failing Elements |
|---|
Manual Checks
The page has a logical tab order The visual layout should be logical in its tab order and users cannot focus elements that are offscreen.
Interactive controls are keyboard focusable Ensure that custom interactive controls are keyboard focusable and that a focus indicator is displayed.
Interactive elements indicate their purpose and state Ensure that interactive elements (such as links and buttons) are distinguishable from non-interactive elements and that they indicate their state.
The user's focus is directed to new content added to the page When new content (such as a dialogue) is added to the page, the user's focus should be directed to it.
User focus is not accidentally trapped in a region Avoid focus being accidentally trapped when a user tabs in and out of controls or regions on page.
Custom controls have associated labels Ensure that custom interactive controls have associated labels, which are provided by aria-label and aria-labelledby attributes.
Custom controls have ARIA roles Ensure that all custom interactive controls have appropriate ARIA roles.
Visual order on the page follows DOM order Ensure that the DOM order matches with the page's visual order, in order to improve navigation for screen readers and other assistive technologies.
Offscreen content is hidden from assistive technology Ensure that offscreen content is hidden through the use of "display:none" styling or the aria-hidden attribute.
HTML5 landmark elements are used to improve navigation Elements such as <main> and <nav> are recommended as they are used by screen readers and other assistive technologies to improve keyboard navigation.
Best Practices
Indicates the recommended, best practices currently in place on the page and highlights the best practices that w3schools.com should incorporate. This includes practices such as protecting pages with HTTPS.Audits
Avoids requesting the geolocation permission on page load When requesting a user's location, provide context or consider tying the request to a user action to avoid confusion and mistrust from users.
Avoids requesting the notification permission on page load When requesting permission to send notifications, provide context or consider tying the request to a user action to avoid confusion and mistrust from users.
Avoids front-end JavaScript libraries with known security vulnerabilities Ensure that the use of third-party scripts is minimal and that only trusted third-party scripts are used as some may contain known security vulnerabilities which may be exploited by attackers.
Ensure CSP is effective against XSS attacks Significantly reduce the risk of cross-site scripting attacks (XSS) by ensuring you have a strong Content Security Policy (CSP).
| Description | Directive | Severity |
|---|---|---|
| script-src directive is missing. This can allow the execution of unsafe scripts. | script-src | High |
| Missing object-src allows the injection of plugins that execute unsafe scripts. Consider setting object-src to 'none' if you can. | object-src | High |
Audits
Allows users to paste into password fields Ensure that password inputs may be pasted into to aid in the user's ability to use password managers and improve security.
Displays images with correct aspect ratio Ensure that image display dimensions match their natural aspect ratio.
Serves images with appropriate resolution For maximum image clarity, ensure images have natural dimensions and are proportional to the display size and pixel ratio.
Fonts with `font-display: optional` are preloaded It is recommended that optional fonts are preloaded.
Audits
Page has the HTML doctype Ensure a doctype is specified to prevent the browser from switching to quirks-mode.
Properly defines charset It is advised to declare a character encoding, optionally via a <meta> tag in the first 1024 bytes of the HTML or in the Content-Type HTTP response header.
Audits
Detected JavaScript libraries Below is a list of all front-end JavaScript libraries that were detected on the page.
Avoids deprecated APIs Avoid deprecated APIs which will eventually be removed the browser.
No browser errors logged to the console Below is a list of all errors logged to the console, which indicate unresolved problems on the site.
No issues in the `Issues` panel in Chrome Devtools There may be unresolved issues logged to Chrome Devtools.
Audits
Does not use HTTPS — 1 insecure request found Ensure that all pages are protected with HTTPS (including those that do not handle sensitive data) as HTTPS prevents tampering and passive listening on communications between the app and its users. Additionally, HTTPS is a prerequisite for HTTP/2 and many new web platform APIs.
| Insecure URL | Request Resolution |
|---|---|
| http://w3schools.com/ | Allowed |
Audits
Missing source maps for large first-party JavaScript Consider deploying source maps for added benefits such as the ability to debug while in production.
| URL | Map URL |
|---|---|
| https://cdn.snigelweb.com/prebid/7.17.0/prebid.js?v=4950-1666165383718 | |
| https://c.amazon-adsystem.com/aax2/apstag.js | https://c.amazon-adsystem.com/aax2/apstag.js.map |
SEO
Indicates how well the page is optimized for ranking in search engines and highlights Search Engine Optimization (SEO) opportunities for w3schools.com. This includes optimizations such as providing meta data.Mobile Friendly
Has a `<meta name="viewport">` tag with `width` or `initial-scale` It is advised to use a '<meta name="viewport">' tag for the optimization of w3schools.com on mobile screens.
Document uses legible font sizes Font sizes of 12px or less are too small to most mobile users without user gestures and further action. Aim for more than 60% of page text to use font sizes greater than 12px.
Tap targets are sized appropriately Interactive elements (such as buttons and links) should be appropriately spaced, sized and easy enough to select or tap with regard to their surrounding elements.
Content Best Practices
Document has a `<title>` element Search engines, screen reader users and other assistive technology users rely on the title to provide an overview of the page and to help determine if the page is relevant to their search.
Document has a meta description Meta descriptions may be used by search engines when displaying a link to the page and should concisely summarize the page's content.
Document has a valid `hreflang` Search engines can be instructed to list specific versions of a page for a given language or region through the use of hreflang links.
Document has a valid `rel=canonical` Search engines can be suggested which URL should be shown in search results through the use of canonical links.
Document avoids plugins The content of plugins cannot be indexed by search engines and many devices either restrict or do not support them.
Crawling and Indexing
Page has successful HTTP status code Avoid pages with unsuccessful HTTP status codes as they may not be indexed by search engines.
Page isn’t blocked from indexing Pages that cannot be crawled by search engines cannot be indexed or included in their search results. Ensure that search engines have permission to crawl all pages that should be indexed.
robots.txt is valid Malformed robots.txt files prevent crawlers from understanding how a site wants to be crawled or indexed, which can be devastating to SEO.
Content Best Practices
Links do not have descriptive text — 1 link found Make use of descriptive link text to assist search engines in understanding the content.
| Link destination | Link Text |
|---|---|
| https://www.w3schools.com/go/index.php | Go |
Image elements do not have `[alt]` attributes Provide short and descriptive alternative text where possible on informative elements.
| Failing Elements |
|---|
Crawling and Indexing
Links are not crawlable Ensure that the 'href' attribute of anchor elements links to the appropriate destination. This allows for more pages of the site to be discovered by search engines.
| Uncrawlable Link |
|---|
Manual Checks
Structured data is valid Structured data can be validated through the use of the Structured Data Testing Tool and the Structured Data Linter.
PWA
Indicates how valid the aspects of a Progressive Web App (PWA) are for the page and highlights opportunities to enable/improve the PWA of w3schools.com. This includes details about web app manifests.PWA Optimized
Content is sized correctly for the viewport Ensure that the width of the app's content matches the width of the viewport, otherwise the app might not be optimized for mobile screens.
Has a `<meta name="viewport">` tag with `width` or `initial-scale` It is advised to use a '<meta name="viewport">' tag for the optimization of w3schools.com on mobile screens.
Installable
Web app manifest or service worker do not meet the installability requirements — 1 reason User engagement may be increased by leveraging the browsers ability to proactively prompt users to add the app to their homescreen.
| Failure reason |
|---|
| No manifest was fetched |
PWA Optimized
Does not register a service worker that controls page and `start_url` A service worker is used to provide Progressive Web Apps the use of features such as working offline, the ability for the app to be added to the homescreen as well as push notifications.
Is not configured for a custom splash screen Themed splash screens ensure a high-quality user experience at launch for app users.
View Data
Does not set a theme color for the address bar. A theme may be applied to the browser address bar, which ideally can be made to match the site.
View Data
Does not provide a valid `apple-touch-icon` iOS users of Progressive Web Apps will benefit from an apple touch icon, which can be defined with 'apple-touch-icon', which must point to a non-transparent 192px (or 180px) square PNG.
Manifest doesn't have a maskable icon Maskable icons are great to ensure that images fill the entire shape when installing the app on a device.
Manual Checks
Site works cross-browser Ensure that the Progressive Web App works correctly across every major browser.
Page transitions don't feel like they block on the network Users perceive apps with responsive, snappy transitions as higher peforming and ensures a great user experience, even on a slow network.
Each page has a URL Ensure that all pages are deep linkable via URL. They should also be unique for the purpose of shareability on social media.
Avg. (All Categories)
Performance
Accessibility
Best Practices
SEO
PWA
0–49 (Fail) 50–89 (Average) 90–100 (Pass)
URL: https://www.w3schools.com/
Updated: 21st October, 2022
1.42 seconds
First Contentful Paint (FCP)
0.02 seconds
First Input Delay (FID) Simulate loading on mobile
Performance
Indicates how well the page is performing and highlights opportunities where performance may be improved for w3schools.com. This includes details about optimizing page load times which can result in a better user experience.Metrics
Speed Index — 2.5 s The time taken for the page contents to be visibly populated.
Cumulative Layout Shift — 0 Cumulative Layout Shift is the measurement of visible elements collective movement within the viewport.
View Data
Other
Eliminate render-blocking resources — Potential savings of 0 ms Resources, such as JavaScript and style sheets, can block the first paint of the page. W3schools.com should consider delivering critical JavaScript/style sheets (JS/CSS) inline and deferring all non-critical JS/CSS.
| URL | Transfer Size (Bytes) | Potential Savings (Ms) |
|---|---|---|
| https://www.w3schools.com/lib/my-learning.js?v=1.0.11 | 4920 | 150 |
Properly size images Images can slow down the page's load time. W3schools.com should consider serving more appropriate-sized images.
Defer offscreen images — Potential savings of 323 KiB Time to Interactive can be slowed down by resources on the page. W3schools.com should consider lazy-loading offscreen and hidden images.
| URL | Resource Size (Bytes) | Potential Savings (Bytes) |
|---|---|---|
| https://www.w3schools.com/spaces/files/priscilla-du-preez-XkKCui44iM0-unsplash.921aa0c0.jpg | 331235 | 331235 |
Minify CSS — Potential savings of 3 KiB Cascading Style Sheets (CSS) files can contribute to network payload sizes. W3schools.com should consider minifying CSS files.
| URL | Transfer Size (Bytes) | Potential Savings (Bytes) |
|---|---|---|
| /* Customize w3schools23.css */
#nav_tutorials,
#nav_references,
#nav_exercises {
margin-top: 0;
} ... | 13307 | 2584 |
Minify JavaScript — Potential savings of 2 KiB JavaScript (JS) files can contribute to network payload sizes and increase script parse times. W3schools.com should consider minifying JS files.
| URL | Transfer Size (Bytes) | Potential Savings (Bytes) |
|---|---|---|
| inline:
MyLearning.loadUser('default');
w3Co... | 15126 | 2393 |
Efficiently encode images Unoptimized images can consume more cellular data than what is necessary.
Enable text compression Text-based resources should be served with compression, such as gzip, deflate or brotli.
Preconnect to required origins Resource hints, such as 'preconnect' or 'dns-prefetch', may assist in establishing early connections to important third-party origins.
Initial server response time was short — Root document took 20 ms It is advised to keep the server response time short for the main document, because all other requests depend on it.
| URL | Time Spent (Ms) |
|---|---|
| https://www.w3schools.com/ | 15.818 |
Avoid multiple page redirects — Potential savings of 630 ms Redirects can cause additional delays before the page can begin loading. W3schools.com should avoid multiple or unnecessary page redirects.
| URL | Time Spent (Ms) |
|---|---|
| http://w3schools.com/ | 630 |
| https://www.w3schools.com/ | 0 |
Preload key requests Key requests can be preloaded by using '<link rel=preload>'. W3schools.com should consider using '<link rel=preload>' to prioritize fetching resources that are currently requested later in page load.
Use video formats for animated content Large GIFs are inefficient for delivering animated content. It is recommended to use MPEG4/WebM videos for animations and PNG/WebP for static images instead of GIF.
Remove duplicate modules in JavaScript bundles Ensure that no duplicate JavaScript modules from bundles exist to reduce bytes consumed by network activity.
Avoid serving legacy JavaScript to modern browsers — Potential savings of 0 KiB Polyfills and transforms enable legacy browsers to use new JavaScript features. For bundled JavaScript it is recommended to adopt a modern script deployment strategy using module/nomodule feature detection. This will reduce the amount of code shipped to modern browsers.
| URL | Potential Savings (Bytes) |
|---|---|
| https://c.amazon-adsystem.com/aax2/apstag.js | 109 |
| https://cdn.snigelweb.com/prebid/7.17.0/prebid.js?v=4950-1666165383718 | 48 |
Preload Largest Contentful Paint image It is recommended to preload images used by LCP elements, to improve LCP time.
Avoids enormous network payloads — Total size was 1,190 KiB Large network payloads can cost users money and are linked to long load times.
| URL | Transfer Size (Bytes) |
|---|---|
| https://www.w3schools.com/spaces/files/priscilla-du-preez-XkKCui44iM0-unsplash.921aa0c0.jpg | 331731 |
| https://cdn.snigelweb.com/prebid/7.17.0/prebid.js?v=4950-1666165383718 | 158655 |
| https://securepubads.g.doubleclick.net/gpt/pubads_impl_2022101801.js | 131682 |
| https://www.w3schools.com/ | 115924 |
| https://www.w3schools.com/howto/img_mountains_wide.jpg | 60880 |
| https://www.w3schools.com/howto/img_nature_wide.jpg | 52326 |
| https://www.googletagmanager.com/gtm.js?id=GTM-KTCFC3S | 48779 |
| https://c.amazon-adsystem.com/aax2/apstag.js | 45047 |
| https://www.w3schools.com/lib/fonts/freckle-face-v9-latin-regular.woff2 | 40139 |
| https://www.w3schools.com/howto/img_snow_wide.jpg | 33735 |
Avoid chaining critical requests — 6 chains found Below is a list of Critical Request Chains, which shows which resources are loaded with a high priority. W3schools.com should consider reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load.
User Timing marks and measures — 6 user timings Make use of the User Timing API to measure an app's real-world performance during key user experiences.
| Name | Type | Start Time (Ms) | Duration (Ms) |
|---|---|---|---|
| lteu | Measure | 459.745 | 0.136 |
| ltpq | Measure | 459.948 | 0.028 |
| loadStarteventUtils | Mark | 459.779 | |
| loadEndeventUtils | Mark | 459.886 | |
| loadStartpixelQueue | Mark | 459.956 | |
| loadEndpixelQueue | Mark | 459.98 |
JavaScript execution time — 0.8 s JavaScript (JS) execution time can be lowered by reducing the time required for parsing, compiling and executing JS. Delivering smaller JS payloads may help with this.
| URL | Total CPU Time (Ms) | Script Evaluation (Ms) | Script Parse (Ms) |
|---|---|---|---|
| https://www.w3schools.com/ | 230.744 | 50.228 | 12.44 |
| https://cdn.snigelweb.com/adengine/w3schools.com/loader.js | 201.508 | 88.62 | 10.828 |
| https://securepubads.g.doubleclick.net/gpt/pubads_impl_2022101801.js | 163.568 | 139.392 | 23.736 |
| https://cdn.snigelweb.com/prebid/7.17.0/prebid.js?v=4950-1666165383718 | 153.708 | 117.936 | 35.36 |
| Unattributable | 144.904 | 8.332 | 0 |
| https://www.w3schools.com/howto/tryhow_js_slideshow_ifr.htm | 141.336 | 9.424 | 6.072 |
| https://cdn.snigelweb.com/argus/argus.js | 85.956 | 83.1 | 2.428 |
| https://www.googletagmanager.com/gtm.js?id=GTM-KTCFC3S | 81.18 | 68.704 | 9.496 |
| https://c.amazon-adsystem.com/aax2/apstag.js | 66.516 | 52.8 | 10.692 |
| https://securepubads.g.doubleclick.net/tag/js/gpt.js | 65.632 | 57.852 | 4.768 |
Minimizes main-thread work — 1.4 s Main-thread work timing can be lowered by reducing the time required for parsing, compiling and executing JS. Delivering smaller JS payloads may help with this.
| Category | Time Spent (Ms) |
|---|---|
| Script Evaluation | 689.044 |
| Other | 243.116 |
| Style & Layout | 198.64 |
| Script Parsing & Compilation | 129.836 |
| Parse HTML & CSS | 75.484 |
| Rendering | 45.132 |
All text remains visible during webfont loads Make use of the font-display CSS feature, which will ensure text is user-visible while webfonts are loading.
Keep request counts low and transfer sizes small — 31 requests • 1,190 KiB It is advised to add a budgets.json file in order to set budgets for the quantity and size of page resources.
| Resource Type | Requests | Transfer Size (Bytes) |
|---|---|---|
| Total | 31 | 1218218 |
| Image | 5 | 496977 |
| Script | 14 | 474661 |
| Document | 2 | 117737 |
| Font | 6 | 110715 |
| Stylesheet | 1 | 13182 |
| Other | 3 | 4946 |
| Media | 0 | 0 |
| Third-party | 11 | 436941 |
Minimize third-party usage — Third-party code blocked the main thread for 70 ms It is advised to either limit, remove or delay the loading of redundant third-party code which may be significantly impacting load performance.
| Third-Party | Transfer Size (Bytes) | Main-Thread Blocking Time (Ms) |
|---|---|---|
| 161293 | 71.588 | |
| 48779 | 0 | |
| 48325 | 0 | |
| 0 | 0 |
Lazy load third-party resources with facades Consider replacing third-party embeds with a facade until they are required (use lazy loading).
Largest Contentful Paint element — 1 element found The element which was identified as the Largest Contentful Paint.
| Element |
|---|
Largest Contentful Paint image was not lazily loaded Above-the-fold images that are lazily loaded render later in the page lifecycle, which can delay the largest contentful paint.
Avoid large layout shifts Below is a list of all DOM elements that contribute to the CLS of the page.
Uses passive listeners to improve scrolling performance Improve the page's scroll performance by marking touch and wheel event listeners as 'passive'.
Avoids `document.write()` Avoid or limit the use of external scripts that are dynamically injected via 'document.write()' as users on slow connections will be delayed by tens of seconds.
Avoid long main-thread tasks — 8 long tasks found Below is a list of the longest tasks on the main thread, which is useful when identifying the worst input delay contributors.
| URL | Start Time (Ms) | Duration (Ms) |
|---|---|---|
| https://securepubads.g.doubleclick.net/gpt/pubads_impl_2022101801.js | 7235 | 157 |
| https://cdn.snigelweb.com/prebid/7.17.0/prebid.js?v=4950-1666165383718 | 6541 | 155 |
| https://cdn.snigelweb.com/adengine/w3schools.com/loader.js | 2843 | 98 |
| https://www.w3schools.com/lib/uic.js?v=1.0.5 | 5160 | 94 |
| https://cdn.snigelweb.com/argus/argus.js | 6991 | 87 |
| https://securepubads.g.doubleclick.net/tag/js/gpt.js | 4321 | 64 |
| https://c.amazon-adsystem.com/aax2/apstag.js | 4621 | 59 |
| https://www.w3schools.com/ | 2010 | 53 |
Avoid non-composited animations It is recommended to avoid non-composited animations which are often janky and increase CLS.
Has a `<meta name="viewport">` tag with `width` or `initial-scale` It is advised to use a '<meta name="viewport">' tag for the optimization of w3schools.com on mobile screens.
Avoids `unload` event listeners The 'unload' event does not fire reliably, causing issues with browser optimizations such as the Back-Forward Cache. It is recommended that 'pagehide' or 'visibilitychange' events are used instead.
Budgets
Performance budget It is advised to keep the quantity and size of all network requests under the targets set by the provided performance budget.
Timing budget It is advised to set a timing budget to monitor the performance of your site.
Audits
Network Requests Below is a list of network requests that were made during page load.
| URL | Protocol | Start Time (Ms) | End Time (Ms) | Transfer Size (Bytes) | Resource Size (Bytes) | Status Code | MIME Type | Resource Type |
|---|---|---|---|---|---|---|---|---|
| http://w3schools.com/ | http/1.1 | 0 | 152.58500003256 | 268 | 0 | 301 | text/html | |
| https://www.w3schools.com/ | h2 | 152.93900016695 | 167.76100010611 | 115924 | 115349 | 200 | text/html | Document |
| https://www.w3schools.com/lib/fonts/fontawesome.woff2?14663396 | h2 | 179.08899998292 | 183.6459999904 | 10664 | 10176 | 200 | application/font-woff2 | Font |
| https://www.w3schools.com/lib/fonts/source-code-pro-v14-latin-regular.woff2 | h2 | 179.32500015013 | 183.32800013013 | 14251 | 13764 | 200 | application/font-woff2 | Font |
| https://www.w3schools.com/lib/fonts/roboto-mono-v13-latin-500.woff2 | h2 | 179.49800007045 | 185.44000014663 | 12975 | 12488 | 200 | application/font-woff2 | Font |
| https://www.w3schools.com/lib/fonts/source-sans-pro-v14-latin-700.woff2 | h2 | 179.71500009298 | 186.3730000332 | 16251 | 15764 | 200 | application/font-woff2 | Font |
| https://www.w3schools.com/lib/fonts/source-sans-pro-v14-latin-600.woff2 | h2 | 179.96600014158 | 187.61100014672 | 16435 | 15948 | 200 | application/font-woff2 | Font |
| https://www.w3schools.com/lib/fonts/freckle-face-v9-latin-regular.woff2 | h2 | 180.24500017054 | 187.0910001453 | 40139 | 39652 | 200 | application/font-woff2 | Font |
| https://www.w3schools.com/lib/w3schools30.css | h2 | 180.49499997869 | 191.18100008927 | 13182 | 63308 | 200 | text/css | Stylesheet |
| https://cdn.snigelweb.com/adengine/w3schools.com/loader.js | h2 | 195.99999999627 | 215.07300017402 | 7058 | 15692 | 200 | application/javascript | Script |
| https://www.w3schools.com/lib/common-deps.js?v=1.0.0 | h2 | 180.83900003694 | 185.81200018525 | 1833 | 2807 | 200 | application/javascript | Script |
| https://www.w3schools.com/lib/user-session.js?v=1.0.2 | h2 | 181.11300002784 | 186.70600000769 | 2692 | 8922 | 200 | application/javascript | Script |
| https://www.w3schools.com/lib/my-learning.js?v=1.0.11 | h2 | 181.32400000468 | 192.32100015506 | 4920 | 18640 | 200 | application/javascript | Script |
| https://www.w3schools.com/lib/uic.js?v=1.0.5 | h2 | 181.52900016867 | 188.85300005786 | 25638 | 70334 | 200 | application/javascript | Script |
| https://www.w3schools.com/lib/w3codecolor.js | h2 | 181.67600012384 | 190.35000004806 | 7315 | 31504 | 200 | application/javascript | Script |
| https://www.googletagmanager.com/gtm.js?id=GTM-KTCFC3S | h2 | 197.77800003067 | 216.87400015071 | 48779 | 126179 | 200 | application/javascript | Script |
| https://www.w3schools.com/howto/tryhow_js_slideshow_ifr.htm | h2 | 226.41899995506 | 231.3050001394 | 1813 | 3516 | 200 | text/html | Document |
| https://www.w3schools.com/spaces/files/priscilla-du-preez-XkKCui44iM0-unsplash.921aa0c0.jpg | h2 | 257.8710000962 | 266.12900011241 | 331731 | 331235 | 200 | image/jpeg | Image |
| https://www.w3schools.com/about/w3codes.png | h2 | 258.29600007273 | 262.69200001843 | 18305 | 17831 | 200 | image/png | Image |
| https://cdn.snigelweb.com/prebid/7.17.0/prebid.js?v=4950-1666165383718 | h2 | 290.98800010979 | 354.30500004441 | 158655 | 556444 | 200 | application/javascript | Script |
| https://c.amazon-adsystem.com/aax2/apstag.js | h2 | 291.39599995688 | 298.06299996562 | 45047 | 180832 | 200 | application/javascript | Script |
| https://securepubads.g.doubleclick.net/tag/js/gpt.js | h2 | 291.80900007486 | 299.1200000979 | 28211 | 80700 | 200 | text/javascript | Script |
| https://adengine.snigelweb.com/w3schools.com/4950-1666165383718/adngin.js | h2 | 292.41600004025 | 314.49200003408 | 387 | 133 | 200 | application/javascript | Script |
| https://cdn.snigelweb.com/argus/argus.js | h2 | 293.55700011365 | 312.59400001727 | 12444 | 36911 | 200 | application/javascript | Script |
| https://www.w3schools.com/howto/img_nature_wide.jpg | h2 | 313.14199999906 | 323.77100014128 | 52326 | 51851 | 200 | image/jpeg | Image |
| https://www.w3schools.com/howto/img_snow_wide.jpg | h2 | 314.36900002882 | 342.90800010785 | 33735 | 33260 | 200 | image/jpeg | Image |
| https://www.w3schools.com/howto/img_mountains_wide.jpg | h2 | 326.00500015542 | 330.62699995935 | 60880 | 60405 | 200 | image/jpeg | Image |
| https://www.google-analytics.com/analytics.js | 334.67900007963 | 10229.184000054 | 0 | 0 | -1 | Script | ||
| https://securepubads.g.doubleclick.net/gpt/pubads_impl_2022101801.js | h2 | 396.25400002114 | 406.36699995957 | 131682 | 387895 | 200 | text/javascript | Script |
| https://securepubads.g.doubleclick.net/pagead/ppub_config?ippd=www.w3schools.com | h2 | 397.52100012265 | 403.52100017481 | 1400 | 1631 | 200 | application/json | XHR |
| https://c.amazon-adsystem.com/bao-csm/aps-comm/aps_csm.js | h2 | 412.18900005333 | 417.76100010611 | 3278 | 6482 | 200 | application/javascript | XHR |
Network Round Trip Times — 0 ms High Network RTT (Round Trip Times) can have a large impact on performance. Providing servers geographically closer to the user could improve performance.
Server Backend Latencies — 0 ms High server latencies indicate the server is overloaded or has a poor backend performance.
Tasks Below is a list of the top-level main thread tasks that executed during page load.
| Start Time (Ms) | End Time (Ms) |
|---|---|
| 171.842 | 13.272 |
| 197.646 | 5.066 |
| 202.721 | 13.096 |
| 221.455 | 23.447 |
| 245.015 | 49.015 |
| 294.27 | 7.68 |
| 303.642 | 10.108 |
| 316.628 | 8.61 |
| 328.549 | 8.847 |
| 342.391 | 13.352 |
| 359.367 | 21.699 |
| 382.924 | 15.961 |
| 398.917 | 14.747 |
| 419.006 | 38.676 |
| 462.103 | 39.201 |
Script Treemap Data Provide as required, for treemap app.
Metrics
First Contentful Paint — 2.5 s The time taken for the first image or text on the page to be rendered.
Time to Interactive — 7.1 s The time taken for the page to become fully interactive.
Total Blocking Time — 290 ms The total blocking time is the sum of all time periods between First Contentful Paint and Time to Interactive (when task length exceeded 50ms).
Largest Contentful Paint — 3.6 s The timing of the largest text or image that is painted.
Audits
Max Potential First Input Delay — 160 ms Users could experience a delay when interacting with the page.
First Meaningful Paint — 2.7 s The time taken for the primary content of the page to be rendered.
Other
Reduce unused CSS — Potential savings of 12 KiB Dead and/or unused rules in Style Sheets (CSS) can contribute to network payload sizes. W3schools.com should consider removing dead rules from style sheets and deferring the loading of CSS not used for above-the-fold content.
| URL | Transfer Size (Bytes) | Potential Savings (Bytes) |
|---|---|---|
| https://www.w3schools.com/lib/w3schools30.css | 13182 | 11900 |
Avoid an excessive DOM size — 939 elements A large DOM (Document Object Model) will increase memory usage, cause longer system calculations as well as costly layout reflows.
| Statistic | Element | Value |
|---|---|---|
| Total DOM Elements | 939 | |
| Maximum DOM Depth | 11 | |
| Maximum Child Elements | 38 |
Other
Reduce unused JavaScript — Potential savings of 310 KiB It is advised to remove unused JavaScript in order to reduce bytes consumed by network activity.
| URL | Transfer Size (Bytes) | Potential Savings (Bytes) |
|---|---|---|
| https://cdn.snigelweb.com/prebid/7.17.0/prebid.js?v=4950-1666165383718 | 158655 | 134608 |
| https://securepubads.g.doubleclick.net/gpt/pubads_impl_2022101801.js | 131682 | 100269 |
| https://c.amazon-adsystem.com/aax2/apstag.js | 45047 | 34411 |
| https://www.googletagmanager.com/gtm.js?id=GTM-KTCFC3S | 48779 | 24273 |
| https://www.w3schools.com/lib/uic.js?v=1.0.5 | 25638 | 23731 |
Serve images in next-gen formats — Potential savings of 206 KiB Consider JPEG 2000, JPEG XR or WebP image formats which provide better compression than PNG and JPEG.
| URL | Resource Size (Bytes) | Potential Savings (Bytes) |
|---|---|---|
| https://www.w3schools.com/spaces/files/priscilla-du-preez-XkKCui44iM0-unsplash.921aa0c0.jpg | 331235 | 163704.8 |
| https://www.w3schools.com/howto/img_mountains_wide.jpg | 60405 | 19593.85 |
| https://www.w3schools.com/howto/img_nature_wide.jpg | 51851 | 18195.6 |
| https://www.w3schools.com/about/w3codes.png | 17831 | 9367.8 |
Serve static assets with an efficient cache policy — 18 resources found W3schools.com can speed up repeat visits by increasing the cache lifetime, which is essentially how long before a cached copy expires.
| URL | Cache TTL (Ms) | Transfer Size (Bytes) |
|---|---|---|
| https://c.amazon-adsystem.com/aax2/apstag.js | 3600000 | 45047 |
| https://www.w3schools.com/spaces/files/priscilla-du-preez-XkKCui44iM0-unsplash.921aa0c0.jpg | 14400000 | 331731 |
| https://www.w3schools.com/howto/img_mountains_wide.jpg | 14400000 | 60880 |
| https://www.w3schools.com/howto/img_nature_wide.jpg | 14400000 | 52326 |
| https://www.w3schools.com/lib/fonts/freckle-face-v9-latin-regular.woff2 | 14400000 | 40139 |
| https://www.w3schools.com/howto/img_snow_wide.jpg | 14400000 | 33735 |
| https://www.w3schools.com/lib/uic.js?v=1.0.5 | 14400000 | 25638 |
| https://www.w3schools.com/about/w3codes.png | 14400000 | 18305 |
| https://www.w3schools.com/lib/fonts/source-sans-pro-v14-latin-600.woff2 | 14400000 | 16435 |
| https://www.w3schools.com/lib/fonts/source-sans-pro-v14-latin-700.woff2 | 14400000 | 16251 |
| https://www.w3schools.com/lib/fonts/source-code-pro-v14-latin-regular.woff2 | 14400000 | 14251 |
| https://www.w3schools.com/lib/w3schools30.css | 14400000 | 13182 |
| https://www.w3schools.com/lib/fonts/roboto-mono-v13-latin-500.woff2 | 14400000 | 12975 |
| https://www.w3schools.com/lib/fonts/fontawesome.woff2?14663396 | 14400000 | 10664 |
| https://www.w3schools.com/lib/w3codecolor.js | 14400000 | 7315 |
| https://www.w3schools.com/lib/my-learning.js?v=1.0.11 | 14400000 | 4920 |
| https://www.w3schools.com/lib/user-session.js?v=1.0.2 | 14400000 | 2692 |
| https://www.w3schools.com/lib/common-deps.js?v=1.0.0 | 14400000 | 1833 |
Image elements do not have explicit `width` and `height` Reduce layout shifts and improve CLS by setting explicit width and height properties on image elements.
| URL |
|---|
First Contentful Paint (3G) — 4954 ms The time taken for the first image or text on the page to be rendered while on a 3G network.
Accessibility
Indicates how accessible the page is and highlights opportunities where the page can be made more accessible to users of w3schools.com. This includes details about various page attributes that can be optimized.Navigation
`[accesskey]` values are unique Access keys assist users with focusing on different parts of the page. Each access key should be unique for proper navigation.
The page contains a heading, skip link, or landmark region It is advised to provide ways to bypass repetitive content, allowing users to navigate the page efficiently.
`[id]` attributes on active, focusable elements are unique Ensure all focusable elements have a unique id value to allow them to be visible to users of assistive technologies, like a screen reader.
No element has a `[tabindex]` value greater than 0 Although technically valid, a tabindex value greater than 0 often creates frustrating experiences for users who rely on assistive technologies.
ARIA
`[aria-*]` attributes match their roles Avoid mismatching 'aria-*' attributes and their 'role' value, as it invalidates the attribute.
`button`, `link`, and `menuitem` elements have accessible names Without accessible names on elements, screen readers will default to announcing a generic name, which means your content will be less accessible to users who rely on screen readers.
`[aria-hidden="true"]` is not present on the document `<body>` If aria-hidden=true is set on the document body, assistive technologies, like a screen reader will work inconsistently.
`[aria-hidden="true"]` elements do not contain focusable descendents Interactive elements within an aria-hidden=true element are unavailable to users of assistive technologies, like a screen reader.
ARIA input fields have accessible names Generic names are announced to users of assistive technologies, like a screen reader, when an input field does not have an accessible name specified.
ARIA `meter` elements have accessible names Without accessible names on elements, screen readers will default to announcing a generic name, which means your content will be less accessible to users who rely on screen readers.
ARIA `progressbar` elements have accessible names Without accessible names on elements, screen readers will default to announcing a generic name, which means your content will be less accessible to users who rely on screen readers.
`[role]`s have all required `[aria-*]` attributes Some ARIA roles have required 'aria-*' attributes, which provide essential information about state and functionality.
Elements with an ARIA `[role]` that require children to contain a specific `[role]` have all required children. Some ARIA parent roles cannot perform their intended functions if specific child roles are not used.
`[role]`s are contained by their required parent element Some ARIA child roles cannot perform their intended functions if specific parent roles are not used.
`[role]` values are valid All ARIA roles require valid values to perform their intended functions.
ARIA toggle fields have accessible names Generic names are announced to users of assistive technologies, like a screen reader, when a toggle field does not have an accessible name specified.
ARIA `tooltip` elements have accessible names Without accessible names on elements, screen readers will default to announcing a generic name, which means your content will be less accessible to users who rely on screen readers.
ARIA `treeitem` elements have accessible names Without accessible names on elements, screen readers will default to announcing a generic name, which means your content will be less accessible to users who rely on screen readers.
`[aria-*]` attributes have valid values ARIA attributes cannot be interpreted with invalid values when used by screen readers and other assistive technologies.
`[aria-*]` attributes are valid and not misspelled ARIA attributes cannot be interpreted with invalid names when used by screen readers and other assistive technologies.
ARIA IDs are unique Ensure all ARIA ID values are unique to prevent elements from being overlooked by assistive technologies, like a screen reader.
Tables and lists
`<dl>`'s contain only properly-ordered `<dt>` and `<dd>` groups, `<script>`, `<template>` or `<div>` elements. Screen readers and other assistive technologies may produce poor and inaccurate output when definition lists are not properly marked up.
Definition list items are wrapped in `<dl>` elements In order for screen readers and other assistive technologies to properly announce definition list items ('<dt>' and '<dd>'), they must be wrapped in parent a '<dl>' element.
Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`). Use proper list structure to aid screen readers and other assistive technologies.
List items (`<li>`) are contained within `<ul>` or `<ol>` parent elements In order for screen readers to announce list items, ensure that list items ('<li>') are contained within parent '<ul>' or '<ol>' tags.
Cells in a `<table>` element that use the `[headers]` attribute refer to table cells within the same table. Screen readers and other assistive technologies have features to make navigating tables easier. Ensure that '<td>' cells using the headers attribute only refer to other cells in the same table, to improve screen reader user experience.
`<th>` elements and elements with `[role="columnheader"/"rowheader"]` have data cells they describe. Screen readers and other assistive technologies have features to make navigating tables easier. Ensure that table headers refer to some set of cells, to improve screen reader user experience.
Names and labels
Document has a `<title>` element Search engines, screen reader users and other assistive technology users rely on the title to provide an overview of the page and to help determine if the page is relevant to their search.
No form fields have multiple labels Having multiple labels for form fields can be confusing to assistive technologies, like a screen reader.
Image elements have `[alt]` attributes Provide short and descriptive alternative text where possible on informative elements.
`<input type="image">` elements have `[alt]` text Input buttons with alternative text assist screen readers and other assistive technology users to understand its purpose.
Links have a discernible name In order to improve the navigation for screen reader and other assistive technology users, use link text that is unique, focusable and discernible.
`<object>` elements have alternate text It is advised that alt text is used on '<object>' elements in order to provide meaning to screen reader and other assistive technology users, as these technologies are unable to translate non-text content.
Internationalization and localization
`<html>` element has a `[lang]` attribute It is advised to provide a lang attribute so that screen readers and other assistive technologies are guaranteed to announce the page's text correctly. When not provided, the user's default language setting will be used which may cause inaccuracies.
`<html>` element has a valid value for its `[lang]` attribute Specify a valid BCP 47 language in order to help screen readers and other assistive technologies announce text properly.
`[lang]` attributes have a valid value Specify a valid BCP 47 language on elements in order to help screen readers and other assistive technologies announce text properly.
Best practices
The document does not use `<meta http-equiv="refresh">` Pages that refresh automatically cause a poor user experience as focus is directed back to the top of the page unexpectedly.
`[user-scalable="no"]` is not used in the `<meta name="viewport">` element and the `[maximum-scale]` attribute is not less than 5. For users with low vision who rely on screen magnification, ensure that zooming is not disabled.
Audio and video
`<video>` elements contain a `<track>` element with `[kind="captions"]` W3schools.com may provide assistance to deaf or hearing-impaired users with captions on videos.
Names and labels
Buttons do not have an accessible name Buttons become unusable as they are announced simply as "button" when the button does not have an accessible name, when used by screen readers and other assistive technologies.
| Failing Elements |
|---|
`<frame>` or `<iframe>` elements do not have a title Screen reader users and other assistive technology users rely on frame titles to describe the contents of frames.
| Failing Elements |
|---|
Form elements do not have associated labels Screen readers and other assistive technologies rely on labels to properly announce form controls.
| Failing Elements |
|---|
Contrast
Background and foreground colors do not have a sufficient contrast ratio. Many (if not most) users find low-contrast text difficult or impossible to read.
| Failing Elements |
|---|
Navigation
Heading elements are not in a sequentially-descending order Properly order all headers and do not skip heading levels to better the navigation and readability for users of assistive technologies, like a screen reader.
| Failing Elements |
|---|
Manual Checks
The page has a logical tab order The visual layout should be logical in its tab order and users cannot focus elements that are offscreen.
Interactive controls are keyboard focusable Ensure that custom interactive controls are keyboard focusable and that a focus indicator is displayed.
Interactive elements indicate their purpose and state Ensure that interactive elements (such as links and buttons) are distinguishable from non-interactive elements and that they indicate their state.
The user's focus is directed to new content added to the page When new content (such as a dialogue) is added to the page, the user's focus should be directed to it.
User focus is not accidentally trapped in a region Avoid focus being accidentally trapped when a user tabs in and out of controls or regions on page.
Custom controls have associated labels Ensure that custom interactive controls have associated labels, which are provided by aria-label and aria-labelledby attributes.
Custom controls have ARIA roles Ensure that all custom interactive controls have appropriate ARIA roles.
Visual order on the page follows DOM order Ensure that the DOM order matches with the page's visual order, in order to improve navigation for screen readers and other assistive technologies.
Offscreen content is hidden from assistive technology Ensure that offscreen content is hidden through the use of "display:none" styling or the aria-hidden attribute.
HTML5 landmark elements are used to improve navigation Elements such as <main> and <nav> are recommended as they are used by screen readers and other assistive technologies to improve keyboard navigation.
Best Practices
Indicates the recommended, best practices currently in place on the page and highlights the best practices that w3schools.com should incorporate. This includes practices such as protecting pages with HTTPS.Audits
Avoids requesting the geolocation permission on page load When requesting a user's location, provide context or consider tying the request to a user action to avoid confusion and mistrust from users.
Avoids requesting the notification permission on page load When requesting permission to send notifications, provide context or consider tying the request to a user action to avoid confusion and mistrust from users.
Avoids front-end JavaScript libraries with known security vulnerabilities Ensure that the use of third-party scripts is minimal and that only trusted third-party scripts are used as some may contain known security vulnerabilities which may be exploited by attackers.
Ensure CSP is effective against XSS attacks Significantly reduce the risk of cross-site scripting attacks (XSS) by ensuring you have a strong Content Security Policy (CSP).
| Description | Directive | Severity |
|---|---|---|
| script-src directive is missing. This can allow the execution of unsafe scripts. | script-src | High |
| Missing object-src allows the injection of plugins that execute unsafe scripts. Consider setting object-src to 'none' if you can. | object-src | High |
Audits
Allows users to paste into password fields Ensure that password inputs may be pasted into to aid in the user's ability to use password managers and improve security.
Displays images with correct aspect ratio Ensure that image display dimensions match their natural aspect ratio.
Serves images with appropriate resolution For maximum image clarity, ensure images have natural dimensions and are proportional to the display size and pixel ratio.
Fonts with `font-display: optional` are preloaded It is recommended that optional fonts are preloaded.
Audits
Page has the HTML doctype Ensure a doctype is specified to prevent the browser from switching to quirks-mode.
Properly defines charset It is advised to declare a character encoding, optionally via a <meta> tag in the first 1024 bytes of the HTML or in the Content-Type HTTP response header.
Audits
Detected JavaScript libraries Below is a list of all front-end JavaScript libraries that were detected on the page.
Avoids deprecated APIs Avoid deprecated APIs which will eventually be removed the browser.
No issues in the `Issues` panel in Chrome Devtools There may be unresolved issues logged to Chrome Devtools.
Audits
Does not use HTTPS — 1 insecure request found Ensure that all pages are protected with HTTPS (including those that do not handle sensitive data) as HTTPS prevents tampering and passive listening on communications between the app and its users. Additionally, HTTPS is a prerequisite for HTTP/2 and many new web platform APIs.
| Insecure URL | Request Resolution |
|---|---|
| http://w3schools.com/ | Allowed |
Audits
Browser errors were logged to the console Below is a list of all errors logged to the console, which indicate unresolved problems on the site.
| Source | Description |
|---|---|
| Failed to load resource: net::ERR_TIMED_OUT |
Missing source maps for large first-party JavaScript Consider deploying source maps for added benefits such as the ability to debug while in production.
| URL | Map URL |
|---|---|
| https://cdn.snigelweb.com/prebid/7.17.0/prebid.js?v=4950-1666165383718 | |
| https://c.amazon-adsystem.com/aax2/apstag.js | https://c.amazon-adsystem.com/aax2/apstag.js.map |
SEO
Indicates how well the page is optimized for ranking in search engines and highlights Search Engine Optimization (SEO) opportunities for w3schools.com. This includes optimizations such as providing meta data.Mobile Friendly
Has a `<meta name="viewport">` tag with `width` or `initial-scale` It is advised to use a '<meta name="viewport">' tag for the optimization of w3schools.com on mobile screens.
Document uses legible font sizes — 99.74% legible text Font sizes of 12px or less are too small to most mobile users without user gestures and further action. Aim for more than 60% of page text to use font sizes greater than 12px.
| Source | Selector | % of Page Text | Font Size |
|---|---|---|---|
| .prev, .next, .text | 0.26% | 11px | |
| 99.74% | ≥ 12px |
Tap targets are sized appropriately — 100% appropriately sized tap targets Interactive elements (such as buttons and links) should be appropriately spaced, sized and easy enough to select or tap with regard to their surrounding elements.
Content Best Practices
Document has a `<title>` element Search engines, screen reader users and other assistive technology users rely on the title to provide an overview of the page and to help determine if the page is relevant to their search.
Document has a meta description Meta descriptions may be used by search engines when displaying a link to the page and should concisely summarize the page's content.
Image elements have `[alt]` attributes Provide short and descriptive alternative text where possible on informative elements.
Document has a valid `hreflang` Search engines can be instructed to list specific versions of a page for a given language or region through the use of hreflang links.
Document has a valid `rel=canonical` Search engines can be suggested which URL should be shown in search results through the use of canonical links.
Document avoids plugins The content of plugins cannot be indexed by search engines and many devices either restrict or do not support them.
Crawling and Indexing
Page has successful HTTP status code Avoid pages with unsuccessful HTTP status codes as they may not be indexed by search engines.
Page isn’t blocked from indexing Pages that cannot be crawled by search engines cannot be indexed or included in their search results. Ensure that search engines have permission to crawl all pages that should be indexed.
robots.txt is valid Malformed robots.txt files prevent crawlers from understanding how a site wants to be crawled or indexed, which can be devastating to SEO.
Content Best Practices
Links do not have descriptive text — 1 link found Make use of descriptive link text to assist search engines in understanding the content.
| Link destination | Link Text |
|---|---|
| https://www.w3schools.com/go/index.php | Go |
Crawling and Indexing
Links are not crawlable Ensure that the 'href' attribute of anchor elements links to the appropriate destination. This allows for more pages of the site to be discovered by search engines.
| Uncrawlable Link |
|---|
Manual Checks
Structured data is valid Structured data can be validated through the use of the Structured Data Testing Tool and the Structured Data Linter.
PWA
Indicates how valid the aspects of a Progressive Web App (PWA) are for the page and highlights opportunities to enable/improve the PWA of w3schools.com. This includes details about web app manifests.PWA Optimized
Content is sized correctly for the viewport Ensure that the width of the app's content matches the width of the viewport, otherwise the app might not be optimized for mobile screens.
Has a `<meta name="viewport">` tag with `width` or `initial-scale` It is advised to use a '<meta name="viewport">' tag for the optimization of w3schools.com on mobile screens.
Installable
Web app manifest or service worker do not meet the installability requirements — 1 reason User engagement may be increased by leveraging the browsers ability to proactively prompt users to add the app to their homescreen.
| Failure reason |
|---|
| No manifest was fetched |
PWA Optimized
Does not register a service worker that controls page and `start_url` A service worker is used to provide Progressive Web Apps the use of features such as working offline, the ability for the app to be added to the homescreen as well as push notifications.
Is not configured for a custom splash screen Themed splash screens ensure a high-quality user experience at launch for app users.
View Data
Does not set a theme color for the address bar. A theme may be applied to the browser address bar, which ideally can be made to match the site.
View Data
Does not provide a valid `apple-touch-icon` iOS users of Progressive Web Apps will benefit from an apple touch icon, which can be defined with 'apple-touch-icon', which must point to a non-transparent 192px (or 180px) square PNG.
Manifest doesn't have a maskable icon Maskable icons are great to ensure that images fill the entire shape when installing the app on a device.
Manual Checks
Site works cross-browser Ensure that the Progressive Web App works correctly across every major browser.
Page transitions don't feel like they block on the network Users perceive apps with responsive, snappy transitions as higher peforming and ensures a great user experience, even on a slow network.
Each page has a URL Ensure that all pages are deep linkable via URL. They should also be unique for the purpose of shareability on social media.
Hosting
Server Location
| Server IP Address: | 13.248.240.135 |
| Continent: | North America |
| Country: | United States  |
| Region: | |
| City: | |
| Longitude: | -97.822 |
| Latitude: | 37.751 |
| Currencies: | USD USN USS |
| Languages: | English |
Web Hosting Provider
| Name | IP Address |
|---|---|
| Amazon Technologies Inc. |
Registration
Domain Registrant
| Private Registration: | No |
| Name: | On behalf of w3schools.com owner |
| Organization: | Identity Protection Service |
| Country: | GB |
| City: | Hayes |
| State: | Middlesex |
| Post Code: | UB3 9TR |
| Email: | 64808f56-1c4b-48bc-a7af-86be2df3d5cc@identity-protect.org |
| Phone: | +44.1483307527 |
Note: Registration information is derived from various sources and may be inaccurate.
Domain Registrar
| Name | IP Address |
|---|---|
| Amazon Registrar, Inc. | 3.171.139.44 |
Security
Visitor Safety
| Mature Content: | Not Likely |
| McAfee WebAdvisor Rating: | Unknown |
| WOT Rating: | |
| WOT Trustworthiness: | 95/100 |
| WOT Child Safety: | 95/100 |
Note: Safety information is not guaranteed.
SSL/TLS Certificate
| Issued To: | *.w3schools.com |
| Issued By: | DigiCert Global G2 TLS RSA SHA256 2020 CA1 |
| Valid From: | 3rd April, 2024 |
| Valid To: | 4th May, 2025 |
| Subject: | CN = *.w3schools.com O = Edgio, Inc. L = Tempe S = US |
| Hash: | 2c437161 |
| Issuer: | CN = DigiCert Global G2 TLS RSA SHA256 2020 CA1 O = DigiCert Inc S = US |
| Version: | 2 |
| Serial Number: | 3204235595661356027967589732951665721 |
| Serial Number (Hex): | 02691D03149F604090757C293BF22C39 |
| Valid From: | 3rd April, 2024 |
| Valid To: | 4th May, 2024 |
| Signature Algorithm (Short Name): | RSA-SHA256 |
| Signature Algorithm (Long Name): | sha256WithRSAEncryption |
| Authority Key Identifier: | keyid:74:85:80:C0:66:C7:DF:37:DE:CF:BD:29:37:AA:03:1D:BE:ED:CD:17 |
| Extended Key Usage: | TLS Web Server Authentication, TLS Web Client Authentication |
| CRL Distribution Points: | Full Name: URI:http://crl3.digicert.com/DigiCertGlobalG2TLSRSASHA2562020CA1-1.crl Full Name: URI:http://crl4.digicert.com/DigiCertGlobalG2TLSRSASHA2562020CA1-1.crl |
| Certificate Policies: | Policy: 2.23.140.1.2.2 CPS: http://www.digicert.com/CPS |
| Authority Information Access: | OCSP - URI:http://ocsp.digicert.com CA Issuers - URI:http://cacerts.digicert.com/DigiCertGlobalG2TLSRSASHA2562020CA1-1.crt |
| SCT List: | Signed Certificate Timestamp: Version : v1 (0x0) Log ID : 4E:75:A3:27:5C:9A:10:C3:38:5B:6C:D4:DF:3F:52:EB: 1D:F0:E0:8E:1B:8D:69:C0:B1:FA:64:B1:62:9A:39:DF Timestamp : Apr 3 07:37:13.459 2024 GMT Extensions: none Signature : ecdsa-with-SHA256 30:46:02:21:00:C9:13:06:D8:96:B3:6B:9E:4C:DC:C0: C7:8F:7B:B0:63:5C:2C:5D:03:61:F1:F1:56:49:51:96: B1:60:42:31:F1:02:21:00:83:4F:2C:D5:13:13:63:6E: 3E:16:4A:C9:CD:E9:F4:0D:B4:66:67:C4:AD:8B:34:59: 3D:41:99:32:3E:13:3F:71 Signed Certificate Timestamp: Version : v1 (0x0) Log ID : 7D:59:1E:12:E1:78:2A:7B:1C:61:67:7C:5E:FD:F8:D0: 87:5C:14:A0:4E:95:9E:B9:03:2F:D9:0E:8C:2E:79:B8 Timestamp : Apr 3 07:37:13.319 2024 GMT Extensions: none Signature : ecdsa-with-SHA256 30:46:02:21:00:9B:D1:4E:F9:8F:CC:5D:9C:63:79:C6: 8F:2C:9C:FC:99:4E:7F:75:D5:F9:9F:D6:70:F5:F6:BE: C0:62:00:2C:4F:02:21:00:8A:5D:DC:62:82:E0:A5:B6: C2:78:8B:55:08:D9:40:65:40:DC:50:D2:E5:8F:3B:2A: 45:CD:55:FD:8D:B3:69:BD Signed Certificate Timestamp: Version : v1 (0x0) Log ID : E6:D2:31:63:40:77:8C:C1:10:41:06:D7:71:B9:CE:C1: D2:40:F6:96:84:86:FB:BA:87:32:1D:FD:1E:37:8E:50 Timestamp : Apr 3 07:37:13.331 2024 GMT Extensions: none Signature : ecdsa-with-SHA256 30:46:02:21:00:8C:DC:74:59:60:6B:39:89:05:16:9E: 28:7C:F1:A8:2D:D8:73:72:87:95:D0:AC:34:5D:42:C9: 97:D6:CA:4D:93:02:21:00:A3:14:9A:93:E7:C1:17:66: 76:9A:39:1E:E1:D1:64:E8:7B:70:EE:2B:7E:AD:7B:6F: 74:A5:A1:F5:78:0B:99:D0 |
| Key Usage: | Digital Signature, Key Encipherment |
| Basic Constraints: | CA:FALSE |
| Subject Alternative Name: | DNS:w3schools.com DNS:*.w3schools.com |
Technical
DNS Lookup
A Records
| Host | IP Address | Class | TTL |
|---|---|---|---|
| w3schools.com. | 13.248.240.135 | IN | 60 |
| w3schools.com. | 76.223.115.82 | IN | 60 |
NS Records
| Host | Nameserver | Class | TTL |
|---|---|---|---|
| w3schools.com. | ns-1409.awsdns-48.org. | IN | 60 |
| w3schools.com. | ns-1939.awsdns-50.co.uk. | IN | 60 |
| w3schools.com. | ns-769.awsdns-32.net. | IN | 60 |
| w3schools.com. | ns-314.awsdns-39.com. | IN | 60 |
MX Records
| Priority | Host | Server | Class | TTL |
|---|---|---|---|---|
| 10 | w3schools.com. | feedback-smtp.eu-west-1.amazonses.com. | IN | 60 |
| 1 | w3schools.com. | aspmx.l.google.com. | IN | 60 |
| 5 | w3schools.com. | alt1.aspmx.l.google.com. | IN | 60 |
| 5 | w3schools.com. | alt2.aspmx.l.google.com. | IN | 60 |
| 10 | w3schools.com. | alt4.aspmx.l.google.com. | IN | 60 |
| 10 | w3schools.com. | alt3.aspmx.l.google.com. | IN | 60 |
SOA Records
| Domain Name | Primary NS | Responsible Email | TTL |
|---|---|---|---|
| w3schools.com. | ns-769.awsdns-32.net. | awsdns-hostmaster.amazon.com. | 900 |
TXT Records
| Host | Value | Class | TTL |
|---|---|---|---|
| w3schools.com. | MS=338A1134735F428FF6729DDF746385742F152781 | IN | 60 |
| w3schools.com. | Sendinblue-code:c1cb221c990a3b197b84632af64eb12a | IN | 60 |
| w3schools.com. | amazonses:9O9JMU+QwMbQv3k+hYpAmauno4fuJMUcWephofXN0yc= | IN | 60 |
| w3schools.com. | v=spf1 | IN | 60 |
HTTP Response Headers
| HTTP-Code: | HTTP/2 200 |
| cache-control: | Public,public |
| content-type: | text/html |
| date: | 22nd September, 2024 |
| expires: | 22nd September, 2024 |
| server: | ECS (dce/2694) |
| content-encoding: | br |
| accept-ranges: | bytes |
| age: | 2358 |
| content-security-policy: | frame-ancestors 'self' https://mycourses.w3schools.com https://pathfinder.w3schools.com; |
| last-modified: | 22nd September, 2024 |
| x-cache: | HIT |
| x-content-security-policy: | frame-ancestors 'self' https://mycourses.w3schools.com https://pathfinder.w3schools.com; |
| x-powered-by: | ASP.NET |
| content-length: | 62469 |
Whois Lookup
| Created: | 21st March, 2000 |
| Changed: | 7th January, 2023 |
| Expires: | 21st March, 2026 |
| Registrar: | Amazon Registrar, Inc. |
| Status: | clientUpdateProhibited clientTransferProhibited clientDeleteProhibited |
| Nameservers: | ns-1409.awsdns-48.org ns-1939.awsdns-50.co.uk ns-314.awsdns-39.com ns-769.awsdns-32.net |
| Owner Name: | On behalf of w3schools.com owner |
| Owner Organization: | Identity Protection Service |
| Owner Street: | PO Box 786 |
| Owner Post Code: | UB3 9TR |
| Owner City: | Hayes |
| Owner State: | Middlesex |
| Owner Country: | GB |
| Owner Phone: | +44.1483307527 |
| Owner Email: | e3f82a15-8888-4d27-9d26-5f2f5a627877@identity-protect.org |
| Admin Name: | On behalf of w3schools.com owner |
| Admin Organization: | Identity Protection Service |
| Admin Street: | PO Box 786 |
| Admin Post Code: | UB3 9TR |
| Admin City: | Hayes |
| Admin State: | Middlesex |
| Admin Country: | GB |
| Admin Phone: | +44.1483307527 |
| Admin Email: | e3f82a15-8888-4d27-9d26-5f2f5a627877@identity-protect.org |
| Tech Name: | On behalf of w3schools.com owner |
| Tech Organization: | Identity Protection Service |
| Tech Street: | PO Box 786 |
| Tech Post Code: | UB3 9TR |
| Tech City: | Hayes |
| Tech State: | Middlesex |
| Tech Country: | GB |
| Tech Phone: | +44.1483307527 |
| Tech Email: | e3f82a15-8888-4d27-9d26-5f2f5a627877@identity-protect.org |
| Full Whois: | Domain Name: w3schools.com
Registry Domain ID: 22974369_DOMAIN_COM-VRSN Registrar WHOIS Server: whois.registrar.amazon Registrar URL: https://registrar.amazon.com Updated Date: 2023-01-07T05:36:02Z Creation Date: 2000-03-21T13:54:41Z Registrar Registration Expiration Date: 2026-03-21T12:54:41Z Registrar: Amazon Registrar, Inc. Registrar IANA ID: 468 Registrar Abuse Contact Email: trustandsafety@support.aws.com Registrar Abuse Contact Phone: +1.2024422253 Domain Status: clientUpdateProhibited https://icann.org/epp#clientUpdateProhibited Domain Status: clientTransferProhibited https://icann.org/epp#clientTransferProhibited Domain Status: clientDeleteProhibited https://icann.org/epp#clientDeleteProhibited Registry Registrant ID: Not Available From Registry Registrant Name: On behalf of w3schools.com owner Registrant Organization: Identity Protection Service Registrant Street: PO Box 786 Registrant City: Hayes Registrant State/Province: Middlesex Registrant Postal Code: UB3 9TR Registrant Country: GB Registrant Phone: +44.1483307527 Registrant Phone Ext: Registrant Fax: +44.1483304031 Registrant Fax Ext: Registrant Email: e3f82a15-8888-4d27-9d26-5f2f5a627877@identity-protect.org Registry Admin ID: Not Available From Registry Admin Name: On behalf of w3schools.com owner Admin Organization: Identity Protection Service Admin Street: PO Box 786 Admin City: Hayes Admin State/Province: Middlesex Admin Postal Code: UB3 9TR Admin Country: GB Admin Phone: +44.1483307527 Admin Phone Ext: Admin Fax: +44.1483304031 Admin Fax Ext: Admin Email: e3f82a15-8888-4d27-9d26-5f2f5a627877@identity-protect.org Registry Tech ID: Not Available From Registry Tech Name: On behalf of w3schools.com owner Tech Organization: Identity Protection Service Tech Street: PO Box 786 Tech City: Hayes Tech State/Province: Middlesex Tech Postal Code: UB3 9TR Tech Country: GB Tech Phone: +44.1483307527 Tech Phone Ext: Tech Fax: +44.1483304031 Tech Fax Ext: Tech Email: e3f82a15-8888-4d27-9d26-5f2f5a627877@identity-protect.org Name Server: NS-314.AWSDNS-39.COM Name Server: NS-769.AWSDNS-32.NET Name Server: NS-1939.AWSDNS-50.CO.UK Name Server: NS-1409.AWSDNS-48.ORG DNSSEC: unsigned URL of the ICANN WHOIS Data Problem Reporting System: http://wdprs.internic.net/ >>> Last update of WHOIS database: 2024-09-22T04:21:41Z <<< For more information on Whois status codes, please visit https://icann.org/epp By submitting a query to the Amazon Registrar, Inc. WHOIS database, you agree to abide by the following terms. The data in Amazon Registrar, Inc.'s WHOIS database is provided by Amazon Registrar, Inc. for the sole purpose of assisting you in obtaining information about domain name accuracy. You agree to use this data only for lawful purposes and further agree not to use this data for any unlawful purpose or to: (1) enable, allow, or otherwise support the transmission by email, telephone, or facsimile of commercial advertising or unsolicited bulk email, or (2) enable high volume, automated, electronic processes to collect or compile this data for any purpose, including mining this data for your own personal or commercial purposes. Amazon Registrar, Inc. reserves the right to restrict or terminate your access to the data if you fail to abide by these terms of use. Amazon Registrar, Inc. reserves the right to modify these terms at any time. Visit Amazon Registrar, Inc. at https://registrar.amazon.com Contact information available here: https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/domain-contact-support.html © 2020, Amazon.com, Inc., or its affiliates |
Nameservers
| Name | IP Address |
|---|---|
| ns-1409.awsdns-48.org | 205.251.197.129 |
| ns-1939.awsdns-50.co.uk | 205.251.199.147 |
| ns-314.awsdns-39.com | 205.251.193.58 |
| ns-769.awsdns-32.net | 205.251.195.1 |
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