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
clinicaltrials.gov/assets/images/nih-nlm-ncbi-logo.png	86400.0 s	230.6 KiB
cdn.ncbi.nlm.nih.gov/core/pinger/pinger.js	3600.0 s	29.7 KiB
/Universal-Federated-Analytics-Min.js?agency=HHS&subagenc...	0.0 ms	9.4 KiB
cdn.ncbi.nlm.nih.gov/core/alerts/alerts.js	3600.0 s	6.1 KiB
dap.digitalgov.gov/web-vitals/dist/web-vitals.attribution.iife.js	0.0 ms	4.5 KiB
/SIE/?Q_ZID=ZN_dikYWqsjiUWN0Q5	3600.0 s	4.6 KiB
clinicaltrials.gov/assets/main/img/AgencyLogo.svg	86400.0 s	9.0 KiB
/dxjsmodule/12.1a2b7192fd54e87d3971.chunk.js?Q_CLIENTVERS...	604800.0 s	35.9 KiB
/dxjsmodule/CoreModule.js?Q_CLIENTVERSION=2.46.0&Q_CLIENT...	604800.0 s	30.9 KiB
iad1.qualtrics.com/WRQualtricsSiteIntercept/Graphic.php?IM=IM_cTi8DT6KZkcCkUm	60.0 s	2.3 KiB
/dxjsmodule/FeedbackButtonModule.js?Q_CLIENTVERSION=2.46....	604800.0 s	19.4 KiB
/dxjsmodule/37.7ea1ffe71ad8c0799cc1.chunk.js?Q_CLIENTVERS...	604800.0 s	18.6 KiB
clinicaltrials.gov/assets/images/ctg-header-logo.svg	86400.0 s	3.4 KiB
clinicaltrials.gov/assets/images/ctg-footer-logo.svg	86400.0 s	1.9 KiB
/dxjsmodule/1.bc67e778235741631577.chunk.js?Q_CLIENTVERSI...	604800.0 s	7.1 KiB
clinicaltrials.gov/assets/images/warning.svg	86400.0 s	1.0 KiB
clinicaltrials.gov/assets/uswds/img/icon-https.svg	86400.0 s	481 B
clinicaltrials.gov/assets/uswds/img/icon-dot-gov.svg	86400.0 s	455 B
clinicaltrials.gov/assets/images/close.png	86400.0 s	368 B
clinicaltrials.gov/assets/uswds/img/us_flag_small.png	86400.0 s	360 B
/dxjsmodule/7.f7df015b06d8a90ce822.chunk.js?Q_CLIENTVERSI...	604800.0 s	1.4 KiB
clinicaltrials.gov/assets/uswds/img/usa-icons/search.svg	86400.0 s	300 B
clinicaltrials.gov/assets/uswds/img/usa-icons/warning.svg	86400.0 s	235 B
clinicaltrials.gov/assets/uswds/img/usa-icons/expand_more.svg	86400.0 s	231 B
clinicaltrials.gov/assets/uswds/img/usa-icons/add.svg	86400.0 s	219 B
clinicaltrials.gov/assets/images/glossary-panel/glossary-icon.svg	86400.0 s	0 B

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.ncbi.nlm.nih.gov/core/pinger/pinger.js	29.7 KiB	1.1 s

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

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: 300 ms 89.1 KiB

URL	Transfer Size	Est Savings
clinicaltrials.gov/styles-K5ERNWXN.css	99.9 KiB	89.1 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: 1.7 s 261.4 KiB

URL	Transfer Size	Est Savings
/gtag/js?id=G-DP2X732JSX&l=pingerDataLayer&cx=c&gtm=4e64h1	147.5 KiB	62.3 KiB
www.googletagmanager.com/gtag/js?id=G-CSLL4ZEK4L	147.2 KiB	62.3 KiB
www.googletagmanager.com/gtm.js?id=GTM-PC9B6M3&l=pingerDataLayer	129.5 KiB	60.4 KiB
clinicaltrials.gov/chunk-FOI7A4D4.js	54.3 KiB	29.4 KiB
clinicaltrials.gov/chunk-J3DBZWUT.js	70.4 KiB	25.7 KiB
/dxjsmodule/12.1a2b7192fd54e87d3971.chunk.js?Q_CLIENTVERS...	35.7 KiB	21.3 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
clinicaltrials.gov/polyfills-6ISPNSXF.js	1.7 s	1.4 s	0.3 ms
Unattributable	926 ms	143 ms	0.0 ms
clinicaltrials.gov/	477 ms	8.1 ms	1.1 ms
clinicaltrials.gov/chunk-PVALZXTS.js	384 ms	371 ms	0.2 ms
www.googletagmanager.com/gtag/js?id=G-CSLL4ZEK4L	295 ms	241 ms	51 ms
/gtag/js?id=G-DP2X732JSX&l=pingerDataLayer&cx=c&gtm=4e64h1	293 ms	234 ms	55 ms
www.googletagmanager.com/gtm.js?id=GTM-PC9B6M3&l=pingerDataLayer	257 ms	195 ms	50 ms
clinicaltrials.gov/scripts-2KLTL4Y7.js	174 ms	87 ms	13 ms
/dxjsmodule/12.1a2b7192fd54e87d3971.chunk.js?Q_CLIENTVERS...	118 ms	85 ms	17 ms
cdn.ncbi.nlm.nih.gov/core/pinger/pinger.js	105 ms	61 ms	15 ms
dap.digitalgov.gov/web-vitals/dist/web-vitals.attribution.iife.js	88 ms	36 ms	1.9 ms
clinicaltrials.gov/styles-K5ERNWXN.css	60 ms	0.0 ms	0.0 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	2.9 s
Other	957 ms
Style & Layout	424 ms
Parse HTML & CSS	266 ms
Script Parsing & Compilation	256 ms
Garbage Collection	150 ms
Rendering	68 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
Pages whose main resource has cache-control:no-store cannot enter back/forward cache.	Not actionable
Back/forward cache is disabled because some JavaScript network request received resource with Cache-Control: no-store header.	Not actionable

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
ClinicalTrials.gov logo `div.grid-row > div.grid-row > div.tablet:grid-col > img.ctg-logo`	clinicaltrials.gov/assets/images/ctg-footer-logo.svg
NIH National Library of Medicine, National Center for Biotechnology Information… `div.grid-row > div.mobile-lg:grid-col-8 > a.logo > img.ncbi-logo`	clinicaltrials.gov/assets/main/img/AgencyLogo.svg
ClinicalTrials.gov `div.usa-navbar > div#basic-logo > a.usa-logo > img.ctg-logo-image`	clinicaltrials.gov/assets/images/ctg-header-logo.svg
Tell us what you think! `body > div.QSIFeedbackButton > button#QSIFeedbackButton-btn > img`	iad1.qualtrics.com/WRQualtricsSiteIntercept/Graphic.php?IM=IM_cTi8DT6KZkcCkUm
header.usa-banner__header > div.usa-banner__inner > div.grid-col-auto > img.usa-banner__header-flag `header.usa-banner__header > div.usa-banner__inner > div.grid-col-auto > img.usa-banner__header-flag`	clinicaltrials.gov/assets/uswds/img/us_flag_small.png

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

●Layout shift culprits

●Document request latency

●Optimize DOM size

●Font display

●Forced reflow

●Improve image delivery

●LCP breakdown

●Modern HTTP

●Optimize viewport for mobile

●Minify CSS

●Minify JavaScript

●Avoids enormous network payloads Total size was 1,409 KiB

●User Timing marks and measures 53 user timings

●Avoid long main-thread tasks 17 long tasks found

●Network Requests

●Network Round Trip Times 120 ms

●Server Backend Latencies 300 ms

●Tasks

●Diagnostics

●Metrics

●Screenshot Thumbnails

●Final Screenshot

●Script Treemap Data

●Resources Summary

●Avoid multiple page redirects

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

●Avoid large layout shifts 2 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.

Contrast

Low-contrast text is difficult or impossible for many users to read. Learn how to provide sufficient color contrast.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
(all filters optional) `ctg-home-search-panel > div.home-search-panel > div.search-panel-header > span`

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
The U.S. government does not review or approve the safety and science of all st… `div.usa-alert__body > div.usa-accordion > div.usa-accordion__heading > button.usa-accordion__button`

○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

●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

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

●Elements use only permitted ARIA attributes

●Document has a `<title>` element

●`<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

●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

○`[accesskey]` values are unique

○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

○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.

○Identical links have the same purpose.

○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

User Experience

Image natural dimensions should be proportional to the display size and the pixel ratio to maximize image clarity. Learn how to provide responsive images.

Why this matters

Performance issues directly impact user engagement and conversion rates.

	URL	Displayed size	Actual size	Expected size
Tell us what you think! `body > div.QSIFeedbackButton > button#QSIFeedbackButton-btn > img`	iad1.qualtrics.com/WRQualtricsSiteIntercept/Graphic.php?IM=IM_cTi8DT6KZkcCkUm	52 x 110	55 x 117	78 x 165

●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

●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

●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

○Use a strong HSTS policy

○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`