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
i.ytimg.com/vi_webp/jxYFg3ygMgk/maxresdefault.webp	7200.0 s	138.2 KiB
i.ytimg.com/vi_webp/fibAxF6t11o/maxresdefault.webp	7200.0 s	130.6 KiB
cdn.ucl.ac.uk/fonts/dm-sans/DMSans[opsz,wght].woff2	14400.0 s	90.6 KiB
cookie-consent.ucl.ac.uk/dist/ucl-consent.ui-full.min.js	14400.0 s	15.1 KiB
cookie-consent.ucl.ac.uk/dist/ucl-consent.blocker.min.js	14400.0 s	12.8 KiB
/home/sites/home/files/styles/content_cards_mobile/public...	604800.0 s	51.3 KiB
/home/sites/home/files/styles/3_2_image_mobile/public/202...	604800.0 s	31.2 KiB
/home/sites/home/files/styles/homepage_hero_mobile/public...	604800.0 s	27.5 KiB
/news/sites/news/files/styles/medium_image/public/gut_mic...	604800.0 s	25.5 KiB
/home/sites/home/files/styles/content_cards_mobile/public...	604800.0 s	23.2 KiB
/news/sites/news/files/styles/medium_image/public/patch_c...	604800.0 s	10.9 KiB
cdn.ucl.ac.uk/logos/ucl/ucl-logo--primary.svg	14400.0 s	943 B
cdn.ucl.ac.uk/logos/ucl/ucl-logo--secondary-inverted.svg	14400.0 s	841 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.

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-0-IMG

nodeLabel: Illuminated portico for UCL 200 event

path: 1,HTML,1,BODY,2,DIV,0,DIV,1,DIV,1,DIV,0,DIV,1,DIV,0,DIV,0,PICTURE,4,IMG

selector: div.homepage-hero__media > div.media > picture > img

snippet: <img loading="eager" width="640" height="360" src="https://www.ucl.ac.uk/home/sites/home/files/styles/homepage_hero_mobile/pu…" alt="Illuminated portico for UCL 200 event">

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
www.ucl.ac.uk/home/themes/custom/indigo/dist/curated-cards.css?tctc50	152 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/footer.css?tctc50	981 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/basic-content.css?tctc50	678 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/whats-on.css?tctc50	760 B
www.ucl.ac.uk/home/modules/contrib/google_tag/js/gtag.ajax.js?tctc50	395 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/homepage-hero.css?tctc50	849 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/whats-on-item.css?tctc50	771 B
www.ucl.ac.uk/home/core/assets/vendor/loadjs/loadjs.min.js?v=4.3.0	1.0 KiB
www.ucl.ac.uk/home/core/assets/vendor/once/once.min.js?v=1.0.1	803 B
www.ucl.ac.uk/home/core/misc/debounce.js?v=10.4.8	770 B
www.ucl.ac.uk/home/themes/contrib/stable/css/media/oembed.formatter.css?tctc50	151 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/highlight-block.css?tctc50	376 B
www.ucl.ac.uk/home/core/misc/drupal.init.js?v=10.4.8	631 B
www.ucl.ac.uk/home/core/misc/drupal.js?v=10.4.8	6.9 KiB	151 ms
www.ucl.ac.uk/home/themes/custom/indigo/dist/quick-link-accordion.css?tctc50	784 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/base.css?tctc50	12.5 KiB
/home/themes/contrib/stable/css/core/components/ajax-prog...	569 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/global-navigation.css?tctc50	1.7 KiB
www.ucl.ac.uk/home/themes/custom/indigo/dist/menu.css?tctc50	374 B
/home/themes/contrib/stable/css/core/components/progress....	450 B
www.ucl.ac.uk/home/core/misc/announce.js?v=10.4.8	1.8 KiB	151 ms
www.ucl.ac.uk/home/core/misc/drupalSettingsLoader.js?v=10.4.8	468 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/feed-widget.css?tctc50	473 B
www.ucl.ac.uk/home/modules/contrib/google_tag/js/gtm.js?tctc50	652 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/base-card.css?tctc50	1.1 KiB
www.ucl.ac.uk/home/themes/custom/indigo/dist/header.css?tctc50	2.1 KiB
www.ucl.ac.uk/home/themes/contrib/stable/css/views/views.module.css?tctc50	290 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/cta.css?tctc50	202 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/pre-footer.css?tctc50	351 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/embed-media.css?tctc50	291 B	151 ms
www.ucl.ac.uk/home/themes/custom/indigo/dist/spotlight.css?tctc50	501 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/back-to-top.css?tctc50	121 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/pre-footer-card.css?tctc50	594 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/accordion.css?tctc50	802 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/social-menu.css?tctc50	391 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/card-link.css?tctc50	778 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/embed-media-item.css?tctc50	308 B
www.ucl.ac.uk/home/core/misc/ajax.js?v=10.4.8	19.5 KiB	301 ms
www.ucl.ac.uk/home/core/misc/progress.js?v=10.4.8	1.9 KiB
www.ucl.ac.uk/home/core/assets/vendor/tabbable/index.umd.min.js?v=6.2.0	2.6 KiB
www.ucl.ac.uk/home/modules/contrib/typogrify/assets/typogrify.css?tctc50	348 B
/home/modules/contrib/oembed_lazyload/modules/oembed_lazy...	765 B
www.ucl.ac.uk/home/core/misc/message.js?v=10.4.8	2.7 KiB
/home/modules/contrib/oembed_lazyload/css/oembed-lazyload...	339 B
/home/modules/contrib/oembed_lazyload/css/oembed-lazyload...	367 B
/home/modules/contrib/paragraphs/css/paragraphs.unpublish...	196 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/quick-links.css?tctc50	247 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/cta-item.css?tctc50	296 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/default.css?tctc50	751 B
www.ucl.ac.uk/home/modules/contrib/google_tag/js/gtag.js?tctc50	666 B
www.ucl.ac.uk/home/themes/contrib/stable/js/ajax.js?v=10.4.8	340 B
www.ucl.ac.uk/home/core/assets/vendor/jquery/jquery.min.js?v=3.7.1	33.7 KiB	602 ms
cookie-consent.ucl.ac.uk/dist/ucl-consent.blocker.min.js	12.8 KiB	913 ms

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
UCL Portico Feb 26 `div.base-card__image > div.media > picture > img`	/home/sites/home/files/styles/content_cards_mobile/public...	51.1 KiB	35.3 KiB
UCL portico Bazaar and Fete 1909 `div.spotlight__image > div.media > picture > img`	/home/sites/home/files/styles/3_2_image_mobile/public/202...	31.0 KiB	23.4 KiB
Illuminated portico for UCL 200 event `div.homepage-hero__media > div.media > picture > img`	/home/sites/home/files/styles/homepage_hero_mobile/public...	27.3 KiB	16.0 KiB
One-to-one meeting student and adviser `div.base-card__image > div.media > picture > img`	/home/sites/home/files/styles/content_cards_mobile/public...	23.0 KiB	15.7 KiB
Gut microbiome changes may signal Parkinson's disease risk `div.base-card > div.base-card__container > div.base-card__image > img.funnelback-image`	/news/sites/news/files/styles/medium_image/public/gut_mic...	25.3 KiB	10.1 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: 778 ms

URL	Time Spent
ucl.ac.uk/	778 ms
www.ucl.ac.uk/	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

Minifying JavaScript files can reduce payload sizes and script parse time. Learn how to minify JavaScript.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 150 ms 21.8 KiB

URL	Transfer Size	Est Savings
www.ucl.ac.uk/home/core/misc/ajax.js?v=10.4.8	19.4 KiB	13.6 KiB
www.ucl.ac.uk/home/core/misc/drupal.js?v=10.4.8	6.8 KiB	5.4 KiB
www.ucl.ac.uk/home/core/misc/tabbingmanager.js?v=10.4.8	3.8 KiB	2.8 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: 150 ms 25.4 KiB

URL	Transfer Size	Est Savings
www.ucl.ac.uk/home/core/assets/vendor/jquery/jquery.min.js?v=3.7.1	33.5 KiB	25.4 KiB

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	863 ms
Style & Layout	724 ms
Script Evaluation	261 ms
Parse HTML & CSS	252 ms
Script Parsing & Compilation	70 ms
Rendering	64 ms

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

●LCP breakdown

●Modern HTTP

●Optimize viewport for mobile

●Max Potential First Input Delay 70 ms

●Minify CSS

●Reduce unused CSS

●Avoids enormous network payloads Total size was 775 KiB

●JavaScript execution time 0.3 s

●Avoid long main-thread tasks 9 long tasks found

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

●Page didn't prevent back/forward cache restoration

●Network Requests

●Network Round Trip Times 10 ms

●Server Backend Latencies 480 ms

●Tasks

●Diagnostics

●Metrics

●Screenshot Thumbnails

●Final Screenshot

●Script Treemap Data

●Resources Summary

●Initial server response time was short Root document took 110 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.

Contrast

Low-contrast text is difficult or impossible for many users to read. Link text that is discernible improves the experience for users with low vision. Learn how to make links distinguishable.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
UCL privacy policy `div#ucl-privacy-banner > div.ucl-privacy-banner__policy-section > p.ucl-privacy-banner__policy-inline > a.ucl-privacy-banner__policy-link`

These are opportunities to improve the legibility of your content.

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
https://www.youtube.com/watch?v=jxYFg3ygMgk `div.field > div.oembed-lazyload > div.ucl-privacy-placeholder > a.ucl-consent-gate__link`
https://www.youtube.com/watch?v=fibAxF6t11o `div.field > div.oembed-lazyload > div.ucl-privacy-placeholder > a.ucl-consent-gate__link`

○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

●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

●`<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

●Touch targets have sufficient size and spacing.

●Heading elements appear in a sequentially-descending order

●Document has a main landmark.

●Deprecated ARIA roles were not used

●All heading elements contain content.

●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

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

○`<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

○Form elements have associated labels

○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>`.

○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

●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

●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

●Page has valid source maps

○Redirects HTTP traffic to HTTPS

○Mitigate clickjacking with XFO or CSP

100

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.

○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

●Links are crawlable

●robots.txt is valid

●Image elements have `[alt]` attributes

●Document has a valid `hreflang`

●Document has a valid `rel=canonical`