Lighthouse Desktop

· 0 checks — Desktop Lighthouse audit -- Performance, Accessibility, Best Practices, and SEO category breakdown.

SCORE

GRADE

FIX

REVIEW

PASS

INFO

Detailed Report

Audit breakdown by category with detailed findings.

Performance

Insights

Remove large, duplicate JavaScript modules from bundles to reduce unnecessary bytes consumed by network activity.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Polyfills and transforms enable older browsers to use new JavaScript features. However, many aren't necessary for modern browsers. Consider modifying your JavaScript build process to not transpile Baseline features, unless you know you must support older browsers. Learn why most sites can deploy ES6+ code without transpiling

Why this matters

Performance issues directly impact user engagement and conversion rates.

3rd party code can significantly impact load performance. Reduce and defer loading of 3rd party code to prioritize your page's content.

Why this matters

Performance issues directly impact user engagement and conversion rates.

A long cache lifetime can speed up repeat visits to your page. Learn more about caching.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Request	Cache TTL	Transfer Size
www.oreilly.com/KxXuCyduA3/oq/qtiMwY_O/uXrEVzLwhDD0Nr/aE0gZA/Cxp/8IWwsPSEB	21600.0 s	180.1 KiB
/KxXuCyduA3/oq/qtiMwY_O/X0rEVzzE/MmwmZA/Tnx/rFAktX0sPAg?v...	21600.0 s	149.9 KiB
/p/1681692/sp/168169200/thumbnail/entry_id/1_7le83llz/ver...	3600.0 s	92.7 KiB
/p/1681692/sp/168169200/thumbnail/entry_id/1_4jl34ett/ver...	3600.0 s	89.9 KiB
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	2378425.0 s	688.9 KiB
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	2379436.0 s	688.9 KiB
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	2543995.0 s	688.9 KiB
/p/1681692/sp/168169200/thumbnail/entry_id/1_nrvzd3wa/ver...	3600.0 s	79.4 KiB
/p/1681692/sp/168169200/thumbnail/entry_id/1_td7km9vj/ver...	3600.0 s	73.2 KiB
/html5/html5lib/v2.86/mwEmbedFrame.php?&wid=_1681692&uico...	152.0 s	58.0 KiB
/html5/html5lib/v2.86/mwEmbedFrame.php?&wid=_1681692&uico...	152.0 s	58.0 KiB
/html5/html5lib/v2.86/mwEmbedFrame.php?&wid=_1681692&uico...	581.0 s	58.1 KiB
/html5/html5lib/v2.86/mwEmbedFrame.php?&wid=_1681692&uico...	581.0 s	58.0 KiB
cdn.oreillystatic.com/oreilly/images/hero-odot-animal-20221104.png	1490647.0 s	324.6 KiB
/oreilly/images/fish_french_grunt_histoirenaturell_cuvier...	1011543.0 s	298.1 KiB
/p/1681692/sp/168169200/embedIframeJs/uiconf_id/47268383/...	152.0 s	21.5 KiB
cdn.oreillystatic.com/images/live-online-training/39040-720x720.jpg	1008035.0 s	183.9 KiB
cdn.oreillystatic.com/images/live-online-training/39420-720x720.jpg	1062776.0 s	163.1 KiB
cdn.oreillystatic.com/oreilly/images/home_sari_greene_720x720.jpg	1062777.0 s	136.5 KiB
cdn.oreillystatic.com/ajax/libs/jquery/3.3.1/jquery.min.js	96017.0 s	29.9 KiB
www.oreilly.com/KxXuCyduA3/oq/qtiMwY_O/X0/QCMLZA/Bi1/QUEVvemop	86400.0 s	28.6 KiB
cdn.oreillystatic.com/oreilly/images/raven_awards_2024_443x442.png	1270167.0 s	107.7 KiB
cdn.oreillystatic.com/oreilly/images/home_neal_ford_720x720.jpg	1007864.0 s	105.0 KiB
cdn.oreillystatic.com/oreilly/images/hero-events-bg-20240611.jpg	1465965.0 s	71.8 KiB
cdn.oreillystatic.com/oreilly/images/kelsey_hightower_color_400x400.jpg	1062776.0 s	55.6 KiB
cdn.oreillystatic.com/ajax/libs/jquery/3.7.0/jquery.min.js	344496.0 s	30.0 KiB
cdn.oreillystatic.com/oreilly/images/ken-kousen-400x400.jpg	1314094.0 s	50.4 KiB
/oreilly/images/home-video-testimonial-thumb1-711x400-202...	1011869.0 s	48.7 KiB
/oreilly/images/home-video-testimonial-thumb3-711x400-202...	1013104.0 s	45.8 KiB
/radar/wp-content/uploads/sites/3/2026/04/Scope-Creep-Kra...	2126130.0 s	45.7 KiB
cdn.oreillystatic.com/oreilly/images/raven_blob_6.jpg	1013108.0 s	40.8 KiB
/oreilly/images/home-video-testimonial-thumb1-711x400-202...	1803153.0 s	41.4 KiB
cdn.oreillystatic.com/assets/css/odot-layout-20250313.css	435094.0 s	25.3 KiB
cdn.oreillystatic.com/oreilly/images/raven_blob_4.jpg	1092819.0 s	28.5 KiB
cdn.oreillystatic.com/oreilly/images/raven_blob_3.jpg	1062776.0 s	28.2 KiB
cdn.oreillystatic.com/oreilly/images/raven_blob_2.jpg	1018664.0 s	25.8 KiB
cdn.oreillystatic.com/oreilly/images/raven_blob_5.jpg	1490647.0 s	24.6 KiB
/oreilly/images/home-video-testimonial-thumb2-400x225-202...	1011869.0 s	15.8 KiB
/html5/html5lib/v2.86//skins/kdark/fonts/icomoon.woff?202...	2379365.0 s	14.1 KiB
cdn.oreillystatic.com/oreilly/images/app-store-logo.png	1268129.0 s	11.1 KiB
/radar/wp-content/uploads/sites/3/2026/04/Trial-by-fire-1...	2212136.0 s	10.8 KiB
cdn.oreillystatic.com/oreilly/images/logo_home_depot.svg	1465965.0 s	9.3 KiB
cdn.oreillystatic.com/oreilly/images/google-play-logo.png	1458454.0 s	9.0 KiB
/radar/wp-content/uploads/sites/3/2026/04/Grief-and-the-n...	1954288.0 s	8.8 KiB
ad.ipredictive.com/d/track/cvt/pixel?acct_id=58840&cache_buster=1776803123	0.0 ms	858 B
/radar/wp-content/uploads/sites/3/2026/04/Architecture-as...	1522427.0 s	8.2 KiB
/radar/wp-content/uploads/sites/3/2026/04/Scenario-planni...	1879427.0 s	8.1 KiB
/radar/wp-content/uploads/sites/3/2026/04/Comprehension-d...	1867730.0 s	7.4 KiB
/radar/wp-content/uploads/sites/3/2026/04/Dark-factories�...	2559555.0 s	7.2 KiB
cdn.oreillystatic.com/assets/css/nav-20260120.css	365991.0 s	4.0 KiB
/radar/wp-content/uploads/sites/3/2026/04/Agents-dont-kno...	1616829.0 s	5.8 KiB
/radar/wp-content/uploads/sites/3/2024/01/Podcast_Cover_G...	2520420.0 s	5.0 KiB
/radar/wp-content/uploads/sites/3/2026/04/AI-is-writing-o...	2040950.0 s	4.6 KiB
www.oreilly.com/KxXuCyduA3/oq/qtiMwY_O/X0/QCMLZA/UnF/Te2ppT3lY	86400.0 s	1.1 KiB
cdn.oreillystatic.com/oreilly/logos/logo_tcs_reverse.svg	1014282.0 s	4.2 KiB
cdn.oreillystatic.com/oreilly/images/logo_electronic_arts.svg	571802.0 s	3.2 KiB
cdn.oreillystatic.com/assets/js/nav-20260120.js	365590.0 s	2.0 KiB
cdn.oreillystatic.com/oreilly/images/roku-tv-logo.png	1805920.0 s	3.1 KiB
cdn.oreillystatic.com/oreilly/images/amazon-appstore-logo.png	1466777.0 s	2.8 KiB
cdn.oreillystatic.com/oreilly/images/logo_nasdaq_reverse.svg	1014280.0 s	2.2 KiB
cdn.oreillystatic.com/oreilly/logos/logo_airbnb_reverse.svg	1334385.0 s	2.0 KiB
cdn.oreillystatic.com/assets/css/2025_font_face.css	365563.0 s	940 B
cdn.oreillystatic.com/oreilly/logos/logo_blue_origin_reverse.svg	1270167.0 s	1.6 KiB
cdn.oreillystatic.com/images/sitewide-headers/oreilly_logo_mark_red.svg	1017525.0 s	1.5 KiB
cdn.oreillystatic.com/oreilly/images/logo_rakuten_reverse.svg	1011545.0 s	1.5 KiB
/v.gif?cd=0&a=27087&d=oreilly.com&u=DFA8060F24384A8656D15...	43200.0 s	147 B
cdn.oreillystatic.com/images/icons/icon_podcast_white.svg	1088971.0 s	689 B
cdn.oreillystatic.com/images/icons/icon_link_white.svg	1803123.0 s	655 B
cdn.oreillystatic.com/images/icons/icon_link_chevron_black.svg	1073495.0 s	514 B
cdn.oreillystatic.com/images/icons/icon_link_chevron_white.svg	1079494.0 s	510 B
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	2378425.0 s	0 B
/oreilly/images/home-video-testimonial-thumb1-711x400-202...	1011869.0 s	0 B
/oreilly/images/home-video-testimonial-thumb3-711x400-202...	1013104.0 s	0 B
/oreilly/images/home-video-testimonial-thumb1-711x400-202...	1803153.0 s	0 B
/oreilly/images/home-video-testimonial-thumb2-400x225-202...	1011869.0 s	0 B
/radar/generative-ai-real-world-podcast/GenAI_in_the_real...	154934.0 s	0 B
/radar/generative-ai-real-world-podcast/GenAI_in_the_real...	154934.0 s	0 B
/radar/generative-ai-real-world-podcast/GenAI_in_the_real...	154934.0 s	0 B
/radar/generative-ai-real-world-podcast/GenAI_in_the_real...	154934.0 s	0 B
/radar/generative-ai-real-world-podcast/GenAI_in_the_real...	154934.0 s	0 B
/radar/generative-ai-real-world-podcast/GenAI_in_the_real...	154934.0 s	0 B
/radar/generative-ai-real-world-podcast/GenAI_in_the_real...	154934.0 s	0 B

Your first network request is the most important. Reduce its latency by avoiding redirects, ensuring a fast server response, and enabling text compression.

Why this matters

Performance issues directly impact user engagement and conversion rates.

A forced reflow occurs when JavaScript queries geometric properties (such as offsetWidth) after styles have been invalidated by a change to the DOM state. This can result in poor performance. Learn more about forced reflows and possible mitigations.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:source label:Source valueType:source-location] map[granularity:1 key:reflowTime label:Total reflow time valueType:ms]]

items: [map[reflowTime:44.783 source:map[type:text value:[unattributed]]]]

Reducing the download time of images can improve the perceived load time of the page and LCP. Learn more about optimizing image size

Why this matters

Performance issues directly impact user engagement and conversion rates.

	URL	Resource Size	Est Savings
section.home-comboGrid > div.content > div.module > ::after `section.home-comboGrid > div.content > div.module > ::after`	/oreilly/images/fish_french_grunt_histoirenaturell_cuvier...	297.6 KiB	258.7 KiB
div.content > div.featuresModual-intro > figure > ::before `div.content > div.featuresModual-intro > figure > ::before`	cdn.oreillystatic.com/oreilly/images/hero-odot-animal-20221104.png	324.1 KiB	225.9 KiB
Arianne Dee Software developer `div.sectionFigure > div.home-experts-slider > div#home-experts-panels > a`	cdn.oreillystatic.com/images/live-online-training/39040-720x720.jpg	183.5 KiB	99.1 KiB
Bruno Gonçalves Senior data scientist `div.sectionFigure > div.home-experts-slider > div#home-experts-panels > a`	cdn.oreillystatic.com/images/live-online-training/39420-720x720.jpg	162.7 KiB	78.4 KiB
section#awardsSection > div.content > figure.sectionFigure > ::after `section#awardsSection > div.content > figure.sectionFigure > ::after`	cdn.oreillystatic.com/oreilly/images/raven_awards_2024_443x442.png	107.4 KiB	75.5 KiB
Sari Greene Cybersecurity practitioner `div.sectionFigure > div.home-experts-slider > div#home-experts-panels > a`	cdn.oreillystatic.com/oreilly/images/home_sari_greene_720x720.jpg	136.1 KiB	51.7 KiB
a.feed-item > div.inner > figure > img `a.feed-item > div.inner > figure > img`	/radar/wp-content/uploads/sites/3/2026/04/Scope-Creep-Kra...	45.1 KiB	44.5 KiB
Kelsey Hightower Software engineer `div.sectionFigure > div.home-experts-slider > div#home-experts-panels > a`	cdn.oreillystatic.com/oreilly/images/kelsey_hightower_color_400x400.jpg	55.3 KiB	29.2 KiB
Ken Kousen Java Champion `div.sectionFigure > div.home-experts-slider > div#home-experts-panels > a`	cdn.oreillystatic.com/oreilly/images/ken-kousen-400x400.jpg	50.1 KiB	24.1 KiB
Neal Ford Software architect `div.sectionFigure > div.home-experts-slider > div#home-experts-panels > a`	cdn.oreillystatic.com/oreilly/images/home_neal_ford_720x720.jpg	104.7 KiB	20.3 KiB
Video thumbnail for 426200_Jose_2min_final_rev7-13 `div.videoHolder > div.videoDisplay > div#kaltura_player_1689279523 > img.playerPoster`	/oreilly/images/home-video-testimonial-thumb1-711x400-202...	41.1 KiB	19.1 KiB
Apple app store `ul.site-footer-list__ul > li > a > img.site-footer__image`	cdn.oreillystatic.com/oreilly/images/app-store-logo.png	10.8 KiB	9.9 KiB
a.feed-item > div.inner > figure > img `a.feed-item > div.inner > figure > img`	/radar/wp-content/uploads/sites/3/2026/04/Trial-by-fire-1...	10.2 KiB	9.6 KiB
Google play store `ul.site-footer-list__ul > li > a > img.site-footer__image`	cdn.oreillystatic.com/oreilly/images/google-play-logo.png	8.7 KiB	7.7 KiB
a.feed-item > div.inner > figure > img `a.feed-item > div.inner > figure > img`	/radar/wp-content/uploads/sites/3/2026/04/Grief-and-the-n...	8.2 KiB	7.7 KiB
a.feed-item > div.inner > figure > img `a.feed-item > div.inner > figure > img`	/radar/wp-content/uploads/sites/3/2026/04/Architecture-as...	7.7 KiB	7.1 KiB
a.feed-item > div.inner > figure > img `a.feed-item > div.inner > figure > img`	/radar/wp-content/uploads/sites/3/2026/04/Scenario-planni...	7.6 KiB	7.0 KiB
a.feed-item > div.inner > figure > img `a.feed-item > div.inner > figure > img`	/radar/wp-content/uploads/sites/3/2026/04/Comprehension-d...	6.9 KiB	6.3 KiB
a.feed-item > div.inner > figure > img `a.feed-item > div.inner > figure > img`	/radar/wp-content/uploads/sites/3/2026/04/Dark-factories�...	6.7 KiB	6.1 KiB
a.feed-item > div.inner > figure > img `a.feed-item > div.inner > figure > img`	/radar/wp-content/uploads/sites/3/2026/04/Agents-dont-kno...	5.3 KiB	4.7 KiB

Optimize LCP by making the LCP image discoverable from the HTML immediately, and avoiding lazy-loading

Why this matters

Performance issues directly impact user engagement and conversion rates.

lhId: page-19-SPAN

nodeLabel: Build the skills your teams need Give your teams the O’Reilly learning platfor…

path: 1,HTML,1,BODY,14,MAIN,2,SPAN

selector: body.homepage > main#maincontent > span#home

snippet: <span class="home" id="home">

Avoid chaining critical requests by reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load.

Why this matters

Performance issues directly impact user engagement and conversion rates.

description: [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints help the browser establish a connection earlier in the page load, saving time when the first request for that origin is made. The following are the origins that the page preconnected to.

title: Preconnected origins

description: Add [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints to your most important origins, but try to use no more than 4.

title: Preconnect candidates

Requests are blocking the page's initial render, which may delay LCP. Deferring or inlining can move these network requests out of the critical path.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL	Transfer Size	Duration
cdn.oreillystatic.com/assets/css/odot-layout-20250313.css	25.3 KiB
cdn.oreillystatic.com/assets/js/nav-20260120.js	2.0 KiB
cdn.oreillystatic.com/assets/css/2025_font_face.css	940 B	221 ms
cdn.oreillystatic.com/assets/css/nav-20260120.css	4.0 KiB

Consider setting font-display to swap or optional to ensure text is consistently visible. swap can be further optimized to mitigate layout shifts with font metric overrides.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL	Est Savings
cdn.oreillystatic.com/fonts/GuardianText/GuardianTextSans-Medium-Web.woff2	20 ms
cdn.oreillystatic.com/fonts/Gilroy/Family/gilroy-regular.woff2	20 ms
cdn.oreillystatic.com/fonts/GuardianText/GuardianTextSans-Regular-Web.woff2	15 ms
cdn.oreillystatic.com/fonts/Gilroy/Family/gilroy-semibold.woff2	15 ms
cdn.oreillystatic.com/fonts/Gilroy/Family/gilroy-bold.woff2	10 ms
cdn.oreillystatic.com/fonts/Gilroy/Family/gilroy-light.woff2	10 ms

These insights are also available in the Chrome DevTools Performance Panel - record a trace to view more detailed information.

Redirects introduce additional delays before the page can be loaded. Learn how to avoid page redirects.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 684 ms

URL	Time Spent
ora.com/	684 ms
www.oreilly.com/	0.0 ms

Time to Interactive is the amount of time it takes for the page to become fully interactive. Learn more about the Time to Interactive metric.

Why this matters

Performance issues directly impact user engagement and conversion rates.

TTI

Diagnostics

Reduce unused rules from stylesheets and defer CSS not used for above-the-fold content to decrease bytes consumed by network activity. Learn how to reduce unused CSS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 40 ms 158.2 KiB

URL	Transfer Size	Est Savings
.js-messagebox{margin:1em 5%;padding:0.5em 2.5%;border:1px solid #ccc;background-color:#fcfcfc; … } …	67.0 KiB	67.0 KiB
.js-messagebox{margin:1em 5%;padding:0.5em 2.5%;border:1px solid #ccc;background-color:#fcfcfc; … } …	67.0 KiB	66.4 KiB
cdn.oreillystatic.com/assets/css/odot-layout-20250313.css	25.0 KiB	24.8 KiB

Consider reducing the time spent parsing, compiling, and executing JS. You may find delivering smaller JS payloads helps with this. Learn how to reduce Javascript execution time.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL	Total CPU Time	Script Evaluation	Script Parse
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	598 ms	403 ms	163 ms
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	277 ms	190 ms	67 ms
Unattributable	262 ms	43 ms	0.0 ms
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	261 ms	182 ms	70 ms
www.oreilly.com/	240 ms	58 ms	3.3 ms
/KxXuCyduA3/oq/qtiMwY_O/X0rEVzzE/MmwmZA/Tnx/rFAktX0sPAg?v...	191 ms	175 ms	8.6 ms
www.oreilly.com/KxXuCyduA3/oq/qtiMwY_O/uXrEVzLwhDD0Nr/aE0gZA/Cxp/8IWwsPSEB	188 ms	173 ms	11 ms
www.googletagmanager.com/gtm.js?id=GTM-5P4V6Z	99 ms	83 ms	11 ms
www.googletagmanager.com/gtag/js?id=G-092EL089CH&cx=c&gtm=4e64h1	57 ms	46 ms	11 ms

Consider reducing the time spent parsing, compiling and executing JS. You may find delivering smaller JS payloads helps with this. Learn how to minimize main-thread work

Why this matters

Performance issues directly impact user engagement and conversion rates.

Category	Time Spent
Script Evaluation	1.5 s
Script Parsing & Compilation	428 ms
Other	248 ms
Style & Layout	150 ms
Parse HTML & CSS	49 ms
Garbage Collection	38 ms
Rendering	29 ms

Many navigations are performed by going back to a previous page, or forwards again. The back/forward cache (bfcache) can speed up these return navigations. Learn more about the bfcache

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failure reason	Failure type
The page has an unload handler in a sub frame.	Actionable

Minifying CSS files can reduce network payload sizes. Learn how to minify CSS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 0.0 ms 5.7 KiB

URL	Transfer Size	Est Savings
cdn.oreillystatic.com/assets/css/odot-layout-20250313.css	25.3 KiB	5.7 KiB

Reduce unused JavaScript and defer loading scripts until they are required to decrease bytes consumed by network activity. Learn how to reduce unused JavaScript.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 0.0 ms 2.1 MiB

URL	Transfer Size	Est Savings
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	688.6 KiB	477.5 KiB
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	688.6 KiB	477.5 KiB
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	688.6 KiB	477.5 KiB
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	688.6 KiB	477.5 KiB
www.googletagmanager.com/gtag/js?id=G-092EL089CH&cx=c&gtm=4e64h1	168.6 KiB	76.8 KiB
www.googletagmanager.com/gtm.js?id=GTM-5P4V6Z	172.1 KiB	76.3 KiB
www.oreilly.com/KxXuCyduA3/oq/qtiMwY_O/uXrEVzLwhDD0Nr/aE0gZA/Cxp/8IWwsPSEB	179.1 KiB	38.9 KiB
/KxXuCyduA3/oq/qtiMwY_O/X0rEVzzE/MmwmZA/Tnx/rFAktX0sPAg?v...	149.5 KiB	30.9 KiB
cdn.oreillystatic.com/ajax/libs/jquery/3.3.1/jquery.min.js	29.6 KiB	22.2 KiB
cdn.oreillystatic.com/ajax/libs/jquery/3.7.0/jquery.min.js	29.6 KiB	21.5 KiB

Large network payloads cost users real money and are highly correlated with long load times. Learn how to reduce payload sizes.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL	Transfer Size
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	688.9 KiB
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	688.9 KiB
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	688.9 KiB
cdn.oreillystatic.com/oreilly/images/hero-odot-animal-20221104.png	324.6 KiB
/oreilly/images/fish_french_grunt_histoirenaturell_cuvier...	298.1 KiB
cdn.oreillystatic.com/images/live-online-training/39040-720x720.jpg	183.9 KiB
www.oreilly.com/KxXuCyduA3/oq/qtiMwY_O/uXrEVzLwhDD0Nr/aE0gZA/Cxp/8IWwsPSEB	180.1 KiB
www.googletagmanager.com/gtm.js?id=GTM-5P4V6Z	172.4 KiB
www.googletagmanager.com/gtag/js?id=G-092EL089CH&cx=c&gtm=4e64h1	168.6 KiB
cdn.oreillystatic.com/images/live-online-training/39420-720x720.jpg	163.1 KiB

Set an explicit width and height on image elements to reduce layout shifts and improve CLS. Learn how to set image dimensions

Why this matters

Performance issues directly impact user engagement and conversion rates.

	URL
logo: Electronic Arts `section.teamsSection > div.content > figure.sectionFigure > img.height_xs`	cdn.oreillystatic.com/oreilly/images/logo_electronic_arts.svg
logo: Blue Origin `section.teamsSection > div.content > figure.sectionFigure > img.height_s`	cdn.oreillystatic.com/oreilly/logos/logo_blue_origin_reverse.svg
logo: Home Depot `section.teamsSection > div.content > figure.sectionFigure > img.height_l`	cdn.oreillystatic.com/oreilly/images/logo_home_depot.svg
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More information about the performance of your application. These numbers don't directly affect the Performance score.

●Max Potential First Input Delay 130 ms

●Layout shift culprits

●Optimize DOM size

●LCP breakdown

●Modern HTTP

●Optimize viewport for mobile

●Minify JavaScript

●Avoid long main-thread tasks 6 long tasks found

●Network Requests

●Network Round Trip Times 160 ms

●Server Backend Latencies 120 ms

●Tasks

●Diagnostics

●Metrics

●Screenshot Thumbnails

●Final Screenshot

●Script Treemap Data

●Resources Summary

●Initial server response time was short Root document took 100 ms

●Avoid large layout shifts 1 layout shift found

○INP breakdown

○User Timing marks and measures

○Avoid non-composited animations

Accessibility

These checks highlight opportunities to improve the accessibility of your web app. Automatic detection can only detect a subset of issues and does not guarantee the accessibility of your web app, so manual testing is also encouraged.

Names and labels

When a button doesn't have an accessible name, screen readers announce it as "button", making it unusable for users who rely on screen readers. Learn how to make buttons more accessible.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
Testimonial video thumbnail 1 `div.content > div.home-testimonial-figure > div.home-testimonial-thumbnails > button#js-testimonialThumbnail1`
Testimonial video thumbnail 2 `div.content > div.home-testimonial-figure > div.home-testimonial-thumbnails > button#js-testimonialThumbnail2`
Testimonial video thumbnail 3 `div.content > div.home-testimonial-figure > div.home-testimonial-thumbnails > button#js-testimonialThumbnail3`
Testimonial video thumbnail 4 `div.content > div.home-testimonial-figure > div.home-testimonial-thumbnails > button#js-testimonialThumbnail4`

Labels ensure that form controls are announced properly by assistive technologies, like screen readers. Learn more about form element labels.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
div.item-text > div.audioPlayer-controls > div.player-bars > input.seek-bar `div.item-text > div.audioPlayer-controls > div.player-bars > input.seek-bar`

These are opportunities to improve the semantics of the controls in your application. This may enhance the experience for users of assistive technology, like a screen reader.

Best practices

Touch targets with sufficient size and spacing help users who may have difficulty targeting small controls to activate the targets. Learn more about touch targets.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
Play `div.inner > div.item-text > div.audioPlayer-controls > button.btn`
div.item-text > div.audioPlayer-controls > div.player-bars > input.seek-bar `div.item-text > div.audioPlayer-controls > div.player-bars > input.seek-bar`
Testimonial video thumbnail 1 `div.content > div.home-testimonial-figure > div.home-testimonial-thumbnails > button#js-testimonialThumbnail1`
Testimonial video thumbnail 2 `div.content > div.home-testimonial-figure > div.home-testimonial-thumbnails > button#js-testimonialThumbnail2`
Testimonial video thumbnail 3 `div.content > div.home-testimonial-figure > div.home-testimonial-thumbnails > button#js-testimonialThumbnail3`
Testimonial video thumbnail 4 `div.content > div.home-testimonial-figure > div.home-testimonial-thumbnails > button#js-testimonialThumbnail4`

These items highlight common accessibility best practices.

○Interactive controls are keyboard focusable

○Interactive elements indicate their purpose and state

○The page has a logical tab order

○Visual order on the page follows DOM order

○User focus is not accidentally trapped in a region

○The user's focus is directed to new content added to the page

○HTML5 landmark elements are used to improve navigation

○Offscreen content is hidden from assistive technology

○Custom controls have associated labels

○Custom controls have ARIA roles

●`[aria-*]` attributes match their roles

●`[aria-hidden="true"]` is not present on the document `<body>`

●`[role]`s have all required `[aria-*]` attributes

●`[role]` values are valid

●`[aria-*]` attributes have valid values

●`[aria-*]` attributes are valid and not misspelled

●Image elements have `[alt]` attributes

●`[user-scalable="no"]` is not used in the `<meta name="viewport">` element and the `[maximum-scale]` attribute is not less than 5.

●ARIA attributes are used as specified for the element's role

●`[aria-hidden="true"]` elements do not contain focusable descendents

●Elements use only permitted ARIA attributes

●Background and foreground colors have a sufficient contrast ratio

●Document has a `<title>` element

●`<frame>` or `<iframe>` elements have a title

●`<html>` element has a `[lang]` attribute

●`<html>` element has a valid value for its `[lang]` attribute

●Links are distinguishable without relying on color.

●Links have a discernible name

●Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`).

●List items (`<li>`) are contained within `<ul>`, `<ol>` or `<menu>` parent elements

●No element has a `[tabindex]` value greater than 0

●Heading elements appear in a sequentially-descending order

●Skip links are focusable.

●Document has a main landmark.

●Deprecated ARIA roles were not used

●Identical links have the same purpose.

○`[accesskey]` values are unique

○`button`, `link`, and `menuitem` elements have accessible names

○Elements with `role="dialog"` or `role="alertdialog"` have accessible names.

○ARIA input fields have accessible names

○ARIA `meter` elements have accessible names

○ARIA `progressbar` elements have accessible names

○Elements with an ARIA `[role]` that require children to contain a specific `[role]` have all required children.

○`[role]`s are contained by their required parent element

○Elements with the `role=text` attribute do not have focusable descendents.

○ARIA toggle fields have accessible names

○ARIA `tooltip` elements have accessible names

○ARIA `treeitem` elements have accessible names

○The page contains a heading, skip link, or landmark region

○`<dl>`'s contain only properly-ordered `<dt>` and `<dd>` groups, `<script>`, `<template>` or `<div>` elements.

○Definition list items are wrapped in `<dl>` elements

○ARIA IDs are unique

○No form fields have multiple labels

○`<html>` element has an `[xml:lang]` attribute with the same base language as the `[lang]` attribute.

○Input buttons have discernible text.

○`<input type="image">` elements have `[alt]` text

○The document does not use `<meta http-equiv="refresh">`

○`<object>` elements have alternate text

○Select elements have associated label elements.

○Cells in a `<table>` element that use the `[headers]` attribute refer to table cells within the same table.

○`<th>` elements and elements with `[role="columnheader"/"rowheader"]` have data cells they describe.

○`[lang]` attributes have a valid value

○`<video>` elements contain a `<track>` element with `[kind="captions"]`

○Tables have different content in the summary attribute and `<caption>`.

○All heading elements contain content.

○Uses ARIA roles only on compatible elements

○Image elements do not have `[alt]` attributes that are redundant text.

○Elements with visible text labels have matching accessible names.

○Tables use `<caption>` instead of cells with the `[colspan]` attribute to indicate a caption.

○`<td>` elements in a large `<table>` have one or more table headers.

Best Practices

General

Deprecated APIs will eventually be removed from the browser. Learn more about deprecated APIs.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Deprecation / Warning	Source
Unload event listeners are deprecated and will be removed.	line 49, col 396

Source maps translate minified code to the original source code. This helps developers debug in production. In addition, Lighthouse is able to provide further insights. Consider deploying source maps to take advantage of these benefits. Learn more about source maps.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL
www.oreilly.com/KxXuCyduA3/oq/qtiMwY_O/uXrEVzLwhDD0Nr/aE0gZA/Cxp/8IWwsPSEB

●Uses HTTPS

●Avoids third-party cookies

●Allows users to paste into input fields

●Avoids requesting the geolocation permission on page load

●Avoids requesting the notification permission on page load

●Displays images with correct aspect ratio

●Serves images with appropriate resolution

●Page has the HTML doctype

●Properly defines charset

●No browser errors logged to the console

●No issues in the `Issues` panel in Chrome Devtools

●Ensure CSP is effective against XSS attacks

●Use a strong HSTS policy

●Ensure proper origin isolation with COOP

●Mitigate DOM-based XSS with Trusted Types

●Detected JavaScript libraries

○Redirects HTTP traffic to HTTPS

○Mitigate clickjacking with XFO or CSP

SEO

These checks ensure that your page is following basic search engine optimization advice. There are many additional factors Lighthouse does not score here that may affect your search ranking, including performance on Core Web Vitals. Learn more about Google Search Essentials.

Content Best Practices

Descriptive link text helps search engines understand your content. Learn how to make links more accessible.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Link destination	Link Text
www.oreilly.com/search/skills/go/	Go
www.oreilly.com/search/skills/go/	Go
www.oreilly.com/online-learning/verifiable-skills.html	Learn more

Format your HTML in a way that enables crawlers to better understand your app’s content.

○Structured data is valid

●Page isn’t blocked from indexing

●Document has a `<title>` element

●Document has a meta description

●Page has successful HTTP status code

●Links are crawlable

●robots.txt is valid

●Image elements have `[alt]` attributes

●Document has a valid `hreflang`

○Document has a valid `rel=canonical`