Lighthouse Mobile

· 0 checks — Mobile 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	172.1 KiB
/KxXuCyduA3/oq/qtiMwY_O/X0rEVzzE/MmwmZA/FCQ/hVwwjR1EPAg?v...	21600.0 s	153.3 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...	2383926.0 s	688.9 KiB
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	2571190.0 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...	437.0 s	58.1 KiB
/html5/html5lib/v2.86/mwEmbedFrame.php?&wid=_1681692&uico...	437.0 s	58.0 KiB
/html5/html5lib/v2.86/mwEmbedFrame.php?&wid=_1681692&uico...	437.0 s	58.0 KiB
/html5/html5lib/v2.86/mwEmbedFrame.php?&wid=_1681692&uico...	437.0 s	58.0 KiB
cdn.cookielaw.org/scripttemplates/202408.1.0/otBannerSdk.js	86400.0 s	110.4 KiB
cdn.oreillystatic.com/oreilly/images/hero-odot-animal-20221104.png	1496149.0 s	324.6 KiB
/oreilly/images/fish_french_grunt_histoirenaturell_cuvier...	1017045.0 s	298.1 KiB
/p/1681692/sp/168169200/embedIframeJs/uiconf_id/47268383/...	437.0 s	21.5 KiB
cdn.oreillystatic.com/images/live-online-training/39040-720x720.jpg	1013537.0 s	183.9 KiB
cdn.oreillystatic.com/images/live-online-training/39420-720x720.jpg	1068278.0 s	163.1 KiB
cdn.oreillystatic.com/oreilly/images/home_sari_greene_720x720.jpg	1068279.0 s	136.5 KiB
cdn.oreillystatic.com/ajax/libs/jquery/3.3.1/jquery.min.js	101519.0 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	1275669.0 s	107.7 KiB
cdn.oreillystatic.com/oreilly/images/home_neal_ford_720x720.jpg	1013366.0 s	105.0 KiB
cdn.oreillystatic.com/oreilly/images/hero-events-bg-20240611.jpg	1471467.0 s	71.8 KiB
cdn.oreillystatic.com/oreilly/images/kelsey_hightower_color_400x400.jpg	1068278.0 s	55.6 KiB
cdn.oreillystatic.com/ajax/libs/jquery/3.7.0/jquery.min.js	349998.0 s	30.0 KiB
cdn.oreillystatic.com/oreilly/images/ken-kousen-400x400.jpg	1319596.0 s	50.4 KiB
/oreilly/images/home-video-testimonial-thumb1-711x400-202...	1017371.0 s	48.7 KiB
/oreilly/images/home-video-testimonial-thumb3-711x400-202...	1018606.0 s	45.8 KiB
/radar/wp-content/uploads/sites/3/2026/04/Scope-Creep-Kra...	2131631.0 s	45.7 KiB
cdn.oreillystatic.com/oreilly/images/raven_blob_6.jpg	1018610.0 s	40.8 KiB
/oreilly/images/home-video-testimonial-thumb1-711x400-202...	1808655.0 s	41.5 KiB
cdn.oreillystatic.com/assets/css/odot-layout-20250313.css	440597.0 s	25.3 KiB
/scripttemplates/otSDKStub.js?did=f2036796-0a59-4891-aa19...	86400.0 s	9.1 KiB
/logos/deacd13b-f3e1-4b01-87a3-f4cf077c0873/1d51e209-d67c...	86400.0 s	7.1 KiB
cdn.oreillystatic.com/oreilly/images/raven_blob_4.jpg	1098321.0 s	28.5 KiB
cdn.oreillystatic.com/oreilly/images/raven_blob_3.jpg	1068278.0 s	28.2 KiB
cdn.oreillystatic.com/oreilly/images/raven_blob_2.jpg	1024166.0 s	25.8 KiB
cdn.oreillystatic.com/oreilly/images/raven_blob_5.jpg	1496149.0 s	24.6 KiB
/oreilly/images/home-video-testimonial-thumb2-400x225-202...	1017371.0 s	15.8 KiB
/html5/html5lib/v2.86//skins/kdark/fonts/icomoon.woff?202...	2383929.0 s	14.1 KiB
cdn.oreillystatic.com/oreilly/images/app-store-logo.png	1273631.0 s	11.1 KiB
cdn.cookielaw.org/logos/static/powered_by_logo.svg	86400.0 s	2.7 KiB
/radar/wp-content/uploads/sites/3/2026/04/Trial-by-fire-1...	2217637.0 s	10.8 KiB
cdn.oreillystatic.com/oreilly/images/logo_home_depot.svg	1471468.0 s	9.3 KiB
cdn.oreillystatic.com/oreilly/images/google-play-logo.png	1463956.0 s	9.0 KiB
/radar/wp-content/uploads/sites/3/2026/04/Grief-and-the-n...	1959789.0 s	8.8 KiB
ad.ipredictive.com/d/track/cvt/pixel?acct_id=58840&cache_buster=1776797621	0.0 ms	858 B
/radar/wp-content/uploads/sites/3/2026/04/Architecture-as...	1527928.0 s	8.2 KiB
/radar/wp-content/uploads/sites/3/2026/04/Scenario-planni...	1884928.0 s	8.1 KiB
/radar/wp-content/uploads/sites/3/2026/04/Comprehension-d...	1873231.0 s	7.4 KiB
/radar/wp-content/uploads/sites/3/2026/04/Dark-factories�...	2565056.0 s	7.2 KiB
cdn.oreillystatic.com/assets/css/nav-20260120.css	371494.0 s	4.0 KiB
/radar/wp-content/uploads/sites/3/2026/04/Agents-dont-kno...	1622330.0 s	5.8 KiB
/radar/wp-content/uploads/sites/3/2024/01/Podcast_Cover_G...	2525921.0 s	5.0 KiB
/radar/wp-content/uploads/sites/3/2026/04/AI-is-writing-o...	2046451.0 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	1019784.0 s	4.2 KiB
cdn.oreillystatic.com/oreilly/images/logo_electronic_arts.svg	577305.0 s	3.2 KiB
cdn.oreillystatic.com/assets/js/nav-20260120.js	371093.0 s	2.0 KiB
cdn.oreillystatic.com/oreilly/images/roku-tv-logo.png	1811422.0 s	3.1 KiB
cdn.oreillystatic.com/oreilly/images/amazon-appstore-logo.png	1472279.0 s	2.8 KiB
cdn.oreillystatic.com/images/sitewide-headers/oreilly_logo_mark_red_@2x.png	1097448.0 s	2.3 KiB
cdn.oreillystatic.com/oreilly/images/logo_nasdaq_reverse.svg	1019783.0 s	2.2 KiB
cdn.oreillystatic.com/oreilly/logos/logo_airbnb_reverse.svg	1339888.0 s	2.0 KiB
cdn.oreillystatic.com/assets/css/2025_font_face.css	371066.0 s	940 B
cdn.oreillystatic.com/oreilly/logos/logo_blue_origin_reverse.svg	1275670.0 s	1.6 KiB
cdn.oreillystatic.com/oreilly/images/logo_rakuten_reverse.svg	1017047.0 s	1.5 KiB
/v.gif?cd=0&a=27087&d=oreilly.com&u=D3112B9F770B7762415B4...	43200.0 s	147 B
cdn.oreillystatic.com/images/icons/icon_podcast_white.svg	1094472.0 s	689 B
cdn.oreillystatic.com/images/icons/icon_link_white.svg	1808624.0 s	655 B
cdn.oreillystatic.com/images/icons/icon_link_chevron_black.svg	1078997.0 s	515 B
cdn.oreillystatic.com/images/icons/icon_link_chevron_white.svg	1084996.0 s	511 B
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	2571190.0 s	0 B
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	2571190.0 s	0 B
/oreilly/images/home-video-testimonial-thumb1-711x400-202...	1017371.0 s	0 B
/oreilly/images/home-video-testimonial-thumb3-711x400-202...	1018606.0 s	0 B
/oreilly/images/home-video-testimonial-thumb1-711x400-202...	1808655.0 s	0 B
/oreilly/images/home-video-testimonial-thumb2-400x225-202...	1017371.0 s	0 B
/radar/generative-ai-real-world-podcast/GenAI_in_the_real...	160434.0 s	0 B
/radar/generative-ai-real-world-podcast/GenAI_in_the_real...	160434.0 s	0 B
/radar/generative-ai-real-world-podcast/GenAI_in_the_real...	160434.0 s	0 B
/radar/generative-ai-real-world-podcast/GenAI_in_the_real...	160434.0 s	0 B
/radar/generative-ai-real-world-podcast/GenAI_in_the_real...	160434.0 s	0 B
/radar/generative-ai-real-world-podcast/GenAI_in_the_real...	160434.0 s	0 B
/radar/generative-ai-real-world-podcast/GenAI_in_the_real...	160434.0 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.

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	43.3 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	19.2 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	8.4 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	7.9 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	6.4 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	5.9 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	5.8 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	5.5 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-16-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	150 ms
cdn.oreillystatic.com/assets/js/nav-20260120.js	2.0 KiB
cdn.oreillystatic.com/assets/css/nav-20260120.css	4.0 KiB	150 ms
cdn.oreillystatic.com/assets/css/2025_font_face.css	940 B	768 ms

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	15 ms
cdn.oreillystatic.com/fonts/GuardianText/GuardianTextSans-Regular-Web.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
cdn.oreillystatic.com/fonts/Gilroy/Family/gilroy-regular.woff2	10 ms
cdn.oreillystatic.com/fonts/Gilroy/Family/gilroy-semibold.woff2	5.0 ms

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

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

The maximum potential First Input Delay that your users could experience is the duration of the longest task. Learn more about the Maximum Potential First Input Delay metric.

Why this matters

Performance issues directly impact user engagement and conversion rates.

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: 1.2 s

URL	Time Spent
oreilly.com/	1.2 s
www.oreilly.com/	0.0 ms

Diagnostics

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 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: 0.0 ms 110.6 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
cdn.oreillystatic.com/assets/css/odot-layout-20250313.css	25.0 KiB	24.8 KiB
	21.1 KiB	18.8 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
www.oreilly.com/	8.8 s	268 ms	13 ms
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	3.1 s	2.1 s	824 ms
Unattributable	1.3 s	421 ms	0.0 ms
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	920 ms	648 ms	219 ms
/KxXuCyduA3/oq/qtiMwY_O/X0rEVzzE/MmwmZA/FCQ/hVwwjR1EPAg?v...	777 ms	679 ms	37 ms
www.oreilly.com/KxXuCyduA3/oq/qtiMwY_O/uXrEVzLwhDD0Nr/aE0gZA/Cxp/8IWwsPSEB	764 ms	702 ms	47 ms
www.googletagmanager.com/gtm.js?id=GTM-5P4V6Z	415 ms	346 ms	54 ms
cdn.cookielaw.org/scripttemplates/202408.1.0/otBannerSdk.js	259 ms	162 ms	41 ms
www.googletagmanager.com/gtag/js?id=G-092EL089CH&cx=c&gtm=4e64h1	249 ms	200 ms	47 ms
/html5/html5lib/v2.86/mwEmbedFrame.php?&wid=_1681692&uico...	195 ms	119 ms	59 ms
/html5/html5lib/v2.86/mwEmbedFrame.php?&wid=_1681692&uico...	167 ms	87 ms	63 ms
/html5/html5lib/v2.86/mwEmbedFrame.php?&wid=_1681692&uico...	165 ms	72 ms	58 ms
/html5/html5lib/v2.86/mwEmbedFrame.php?&wid=_1681692&uico...	129 ms	58 ms	55 ms
www.oreilly.com/KxXuCyduA3/oq/qtiMwY_O/X0/QCMLZA/Bi1/QUEVvemop	63 ms	48 ms	5.8 ms
/p/1681692/sp/168169200/embedIframeJs/uiconf_id/47268383/...	52 ms	25 ms	8.1 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
Other	8.9 s
Script Evaluation	6.0 s
Script Parsing & Compilation	1.5 s
Style & Layout	515 ms
Parse HTML & CSS	206 ms
Garbage Collection	172 ms
Rendering	147 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

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 2.2 MiB

URL	Transfer Size	Est Savings
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	688.6 KiB	478.9 KiB
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	688.6 KiB	478.9 KiB
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	688.6 KiB	478.9 KiB
/html5/html5lib/v2.86/load.php?debug=false&lang=en&module...	688.6 KiB	478.9 KiB
www.googletagmanager.com/gtag/js?id=G-092EL089CH&cx=c&gtm=4e64h1	168.6 KiB	76.6 KiB
www.googletagmanager.com/gtm.js?id=GTM-5P4V6Z	172.1 KiB	75.4 KiB
cdn.cookielaw.org/scripttemplates/202408.1.0/otBannerSdk.js	110.3 KiB	58.1 KiB
www.oreilly.com/KxXuCyduA3/oq/qtiMwY_O/uXrEVzLwhDD0Nr/aE0gZA/Cxp/8IWwsPSEB	171.1 KiB	36.4 KiB
/KxXuCyduA3/oq/qtiMwY_O/X0rEVzzE/MmwmZA/FCQ/hVwwjR1EPAg?v...	152.9 KiB	31.7 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
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.googletagmanager.com/gtm.js?id=GTM-5P4V6Z	172.5 KiB
www.oreilly.com/KxXuCyduA3/oq/qtiMwY_O/uXrEVzLwhDD0Nr/aE0gZA/Cxp/8IWwsPSEB	172.1 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
/KxXuCyduA3/oq/qtiMwY_O/X0rEVzzE/MmwmZA/FCQ/hVwwjR1EPAg?v...	153.3 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
logo: AirBnB `section.teamsSection > div.content > figure.sectionFigure > img.height_s`	cdn.oreillystatic.com/oreilly/logos/logo_airbnb_reverse.svg
Amazon appstore `ul.site-footer-list__ul > li > a > img.site-footer__image`	cdn.oreillystatic.com/oreilly/images/amazon-appstore-logo.png
Google play store `ul.site-footer-list__ul > li > a > img.site-footer__image`	cdn.oreillystatic.com/oreilly/images/google-play-logo.png
Roku Players and TVs `ul.site-footer-list__ul > li > a > img.site-footer__image`	cdn.oreillystatic.com/oreilly/images/roku-tv-logo.png
Apple app store `ul.site-footer-list__ul > li > a > img.site-footer__image`	cdn.oreillystatic.com/oreilly/images/app-store-logo.png
logo: TCS `section.teamsSection > div.content > figure.sectionFigure > img.height_s`	cdn.oreillystatic.com/oreilly/logos/logo_tcs_reverse.svg
logo: Nasdaq `section.teamsSection > div.content > figure.sectionFigure > img.height_s`	cdn.oreillystatic.com/oreilly/images/logo_nasdaq_reverse.svg
logo: Rakuten `section.teamsSection > div.content > figure.sectionFigure > img.height_s`	cdn.oreillystatic.com/oreilly/images/logo_rakuten_reverse.svg
O'Reilly home `div#site-footer-container > section#site-footer-subfooter > a.footer-subfooterLogo > img#site-footer-subfooter-logo`	cdn.oreillystatic.com/images/sitewide-headers/oreilly_logo_mark_red_@2x.png

More information about the performance of your application. These numbers don't directly affect the Performance score.

●Layout shift culprits

●Optimize DOM size

●Forced reflow

●LCP breakdown

●Modern HTTP

●Optimize viewport for mobile

●Minify JavaScript

●Avoid long main-thread tasks 20 long tasks found

●Avoid non-composited animations 1 animated element found

●Network Requests

●Network Round Trip Times 160 ms

●Server Backend Latencies 160 ms

●Tasks

●Diagnostics

●Metrics

●Screenshot Thumbnails

●Final Screenshot

●Script Treemap Data

●Resources Summary

●Initial server response time was short Root document took 90 ms

●Avoid large layout shifts 11 layout shifts found

○INP breakdown

○User Timing marks and measures

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

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

●`[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

○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
www.oreilly.com/privacy-cookies.html	More information

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`