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.

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.

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

value: no origins were preconnected

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
/css2?family=Roboto:wght@300;400;500;700&family=YouTube+S...	15.4 KiB	400 ms
/s/_/ytmainappweb/_/ss/k=ytmainappweb.kevlar_base.yAlYZ9F...	271.8 KiB	442 ms
www.youtube.com/s/desktop/4329498d/jsbin/spf.vflset/spf.js	11.9 KiB
www.youtube.com/s/desktop/4329498d/jsbin/network.vflset/network.js	4.9 KiB
/s/desktop/4329498d/jsbin/www-i18n-constants-en_US.vflset...	1.6 KiB
www.youtube.com/s/desktop/4329498d/jsbin/scheduler.vflset/scheduler.js	3.1 KiB
www.youtube.com/s/desktop/4329498d/cssbin/www-onepick.css	343 B
/s/desktop/4329498d/cssbin/www-main-desktop-home-page-ske...	1.0 KiB
/s/desktop/4329498d/jsbin/webcomponents-sd.vflset/webcomp...	21.0 KiB
/s/desktop/4329498d/jsbin/intersection-observer.min.vflse...	2.0 KiB
/s/desktop/4329498d/jsbin/custom-elements-es5-adapter.vfl...	781 B
/s/desktop/4329498d/jsbin/web-animations-next-lite.min.vf...	14.1 KiB
/s/desktop/4329498d/cssbin/www-main-desktop-watch-page-sk...	1.4 KiB

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.gstatic.com/eureka/clank/147/cast_sender.js	86400.0 s	13.1 KiB

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: 278 ms

URL	Time Spent
youtube.com/	278 ms
www.youtube.com/	0.0 ms

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.

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: 200 ms 333.8 KiB

URL	Transfer Size	Est Savings
/s/_/ytmainappweb/_/ss/k=ytmainappweb.kevlar_base.yAlYZ9F...	271.6 KiB	262.3 KiB
www.youtube.com/s/player/b174a5bb/www-player.css	56.6 KiB	56.6 KiB
/css2?family=Roboto:wght@300;400;500;700&family=YouTube+S...	14.9 KiB	14.9 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: 880 ms 1.6 MiB

URL	Transfer Size	Est Savings
/s/_/ytmainappweb/_/js/k=ytmainappweb.kevlar_base.en_US.I...	1.8 MiB	1.1 MiB
www.youtube.com/s/player/b174a5bb/player_es6.vflset/en_US/base.js	639.3 KiB	467.1 KiB
www.youtube.com/s/player/b174a5bb/player_es6.vflset/en_US/remote.js	34.3 KiB	26.8 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
/s/_/ytmainappweb/_/js/k=ytmainappweb.kevlar_base.en_US.I...	1.1 s	821 ms	166 ms
/s/desktop/4329498d/jsbin/web-animations-next-lite.min.vf...	571 ms	391 ms	0.9 ms
Unattributable	414 ms	141 ms	0.0 ms
www.youtube.com/s/player/b174a5bb/player_es6.vflset/en_US/base.js	164 ms	113 ms	46 ms
www.youtube.com/	131 ms	13 ms	21 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	1.8 s
Other	430 ms
Script Parsing & Compilation	243 ms
Parse HTML & CSS	108 ms
Style & Layout	95 ms
Garbage Collection	52 ms
Rendering	12 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
Pages with cache-control:no-store header cannot enter back/forward cache.	Actionable
ServiceWorker was unregistered while a page was in back/forward cache.	Not actionable

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
/s/_/ytmainappweb/_/js/k=ytmainappweb.kevlar_base.en_US.I...	1.8 MiB
www.youtube.com/s/player/b174a5bb/player_es6.vflset/en_US/base.js	639.4 KiB
/s/_/ytmainappweb/_/ss/k=ytmainappweb.kevlar_base.yAlYZ9F...	271.8 KiB
www.youtube.com/	76.8 KiB
www.youtube.com/s/player/b174a5bb/www-player.css	56.6 KiB
fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2	36.7 KiB
www.youtube.com/s/player/b174a5bb/player_es6.vflset/en_US/remote.js	34.3 KiB
/s/youtubesans/v32/Qw38ZQNGEDjaO2m6tqIqX5E-AVS5_rSejo46_P...	31.5 KiB
www.google.com/js/th/cdHZnmAh7yL5wO3Dlc3wxOFdaDuUvCTre1L4S51GVXg.js	23.1 KiB
www.youtube.com/s/player/b174a5bb/player_es6.vflset/en_US/offline.js	23.1 KiB

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

●Layout shift culprits

●Optimize DOM size

●Font display

●Forced reflow

●Improve image delivery

●LCP breakdown

●Modern HTTP

●Optimize viewport for mobile

●Minify CSS

●Minify JavaScript

●User Timing marks and measures 33 user timings

●Avoid long main-thread tasks 5 long tasks found

●Image elements have explicit `width` and `height`

●Network Requests

●Network Round Trip Times 30 ms

●Server Backend Latencies 110 ms

●Tasks

●Diagnostics

●Metrics

●Screenshot Thumbnails

●Final Screenshot

●Script Treemap Data

●Resources Summary

●Initial server response time was short Root document took 130 ms

●Avoid large layout shifts 6 layout shifts found

○INP breakdown

○LCP request discovery

○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.

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
About `ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-primary > a`
Press `ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-primary > a`
Copyright `ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-primary > a`
Contact us `ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-primary > a`
Creators `ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-primary > a`
Developers `ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-primary > a`
Terms `ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-secondary > a`
Privacy `ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-secondary > a`
How YouTube works `ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-secondary > a`
Test new features `ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-secondary > a`

These items highlight common accessibility best practices.

Visible text labels that do not match the accessible name can result in a confusing experience for screen reader users. Learn more about accessible names.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
Reject all `div.eom-button-row > ytd-button-renderer.style-scope > yt-button-shape > button.yt-spec-button-shape-next`
Accept all `div.eom-button-row > ytd-button-renderer.style-scope > yt-button-shape > button.yt-spec-button-shape-next`

○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

●Buttons have an accessible name

●Form elements have associated labels

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

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

●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

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

●ARIA `tooltip` elements have accessible names

●Background and foreground colors have a sufficient contrast ratio

●Document has a `<title>` element

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

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

●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

●Document has a main landmark.

●Deprecated ARIA roles were not used

●Identical links have the same purpose.

○`[accesskey]` values are unique

○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

○ARIA toggle fields 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

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

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

○Image elements have `[alt]` attributes

○Input buttons have discernible text.

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

○Links are distinguishable without relying on color.

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

○`<object>` elements have alternate text

○Select elements have associated label elements.

○Skip links are focusable.

○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.

○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.

100

Best Practices

General

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	Map URL
www.youtube.com/s/player/b174a5bb/player_es6.vflset/en_US/base.js
/s/_/ytmainappweb/_/js/k=ytmainappweb.kevlar_base.en_US.I...
www.youtube.com/
/s/desktop/4329498d/jsbin/webcomponents-sd.vflset/webcomp...	/s/desktop/4329498d/jsbin/webcomponents-sd.vflset/blaze-o...
/s/desktop/4329498d/jsbin/web-animations-next-lite.min.vf...	/s/desktop/4329498d/jsbin/web-animations-next-lite.min.vf...
/s/desktop/4329498d/jsbin/custom-elements-es5-adapter.vfl...	/s/desktop/4329498d/jsbin/custom-elements-es5-adapter.vfl...
www.google.com/js/th/cdHZnmAh7yL5wO3Dlc3wxOFdaDuUvCTre1L4S51GVXg.js

●Uses HTTPS

●Avoids deprecated APIs

●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

●Use a strong HSTS policy

●Ensure proper origin isolation with COOP

●Detected JavaScript libraries

○Redirects HTTP traffic to HTTPS

○Ensure CSP is effective against XSS attacks

○Mitigate clickjacking with XFO or CSP

○Mitigate DOM-based XSS with Trusted Types

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.

Crawling and Indexing

Search engines may use `href` attributes on links to crawl websites. Ensure that the `href` attribute of anchor elements links to an appropriate destination, so more pages of the site can be discovered. Learn how to make links crawlable

Why this matters

Performance issues directly impact user engagement and conversion rates.

Uncrawlable Link
div.ytp-title-expanded-overlay > div.ytp-title-expanded-heading > div.ytp-title-expanded-title > a `div.ytp-title-expanded-overlay > div.ytp-title-expanded-heading > div.ytp-title-expanded-title > a`
div.ytp-chrome-top > div.ytp-title > div.ytp-title-text > a.ytp-title-link `div.ytp-chrome-top > div.ytp-title > div.ytp-title-text > a.ytp-title-link`
div.ytp-overlays-container > div.ytp-overlay-top-left > div.ytp-paid-content-overlay > a.ytp-paid-content-overlay-link `div.ytp-overlays-container > div.ytp-overlay-top-left > div.ytp-paid-content-overlay > a.ytp-paid-content-overlay-link`
div#ytp-id-6 > div.ytp-playlist-menu-header > div.ytp-playlist-menu-title > a.ytp-playlist-menu-title-name `div#ytp-id-6 > div.ytp-playlist-menu-header > div.ytp-playlist-menu-title > a.ytp-playlist-menu-title-name`
div#movie_player > div#ytp-id-9 > div.ytp-share-panel-inner-content > a.ytp-share-panel-link `div#movie_player > div#ytp-id-9 > div.ytp-share-panel-inner-content > a.ytp-share-panel-link`

To appear in search results, crawlers need access to your app.

○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 have descriptive text

●robots.txt is valid

●Document has a valid `hreflang`

●Document has a valid `rel=canonical`

○Image elements have `[alt]` attributes