react.dev

The website react.dev was graded on March 19th, 2023 for speed, design, security, accessibility, search, social, advertising and technology.

Overall Grade

react.dev achieved an overall grade of 64 out of 100 based on 121 website tests and scanning for over 3,000 website technologies

Speed

Score: 88 / 100

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Design

Score: 91 / 100

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Security

Score: 100 / 100

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Accessibility

Score: 93 / 100

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Search

Score: 90 / 100

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Social

30 / 100

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Advertising

0 / 100

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Technology

21 / 100

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SPEED

A slow website reflects poorly on any business with the majority of people expecting a page to load in less than two seconds and Google now taking website speed into account for search result rankings.

Speed Grade

react.dev achieved a speed grade of 88 out of 100 based on 33 speed tests

Speed Test Summary

Failed: 0

Warnings: 3

Passed: 23

Not Applicable: 7

Speed Test Results

JavaScript execution took 0.5 seconds. When JavaScript takes a long time to execute it can slow down website performance.	Passed	3
The size of the document object model was 1731 elements. A large model can slow down a website by increasing the memory required and time taken to calculate and display changes.	Warnings	2
No duplicate Javascript was detected. Duplicate JavaScript modules can slow down a website by requiring unnecessary downloads.	Passed	3
No inefficient animated content was detected. Inefficient animated content formats such as animated GIFs should be replaced by video.	Passed	3
The first contentful paint took 0.3 seconds. This measures how long it takes a browser to render the first piece of content when someone visits a website.	Passed	3
The time to interactive was 0.9 seconds. This measures how long it takes a page to become fully interactive.	Passed	3
The largest contentful paint took 0.4 seconds. This approximates when the main content of the page is visible to users.	Passed	3
Lazy loading of the largest contentful paint image Lazily loading above the fold images can negatively affect performance.	Not applicable	4
No legacy JavaScript was detected. Avoid serving legacy JavaScript to modern browsers, only serving it to older browsers that require it.	Passed	3
The main thread was busy for 1.1 seconds. When the main thread is busy the website may not respond quickly to user interactions.	Passed	3
The first input delay was 0.1 seconds. This measures the time from when a user first interacts with a website to the time when the browser is actually able to respond to that interaction.	Passed	3
Modern image formats null	Not applicable	4
Network server latency A high latency is an indication that the backend server is overloaded or performing poorly.	Not applicable	4
Usage of document.write() was not detected. External scripts dynamically injected via document.write() can delay page load by tens of seconds.	Passed	3
Offscreen and hidden images were lazily loaded. Lazy-loading offscreen and hidden images after all critical resources have finished loading can significantly increase website performance.	Passed	3
Preloading of optional fonts Preload optional fonts so that first-time visitors can use them and to prevent layout shifting.	Not applicable	4
The largest contentful paint image was preloaded. The image used by the largest contentful paint element should be preloaded to maximize performance.	Passed	3
Excessive page redirects were not detected. Avoid multiple page redirects as they introduce additional delays before the page can be loaded.	Passed	3
Render blocking resources Delivering critical JavaScript and CSS inline and deferring all non-critical JavaScript and CSS can help prevent render blocking.	Not applicable	4
The server response time was 0.1 seconds. Server response times can be improved by optimizing server-side code or upgrading server hardware.	Passed	3
The speed index was 0.5 seconds. This indicates how quickly the contents of a page are visibly populated.	Passed	3
Lazy loading of third party resources Some third-party embeds can be lazy loaded and replaced with a facade until they are required.	Not applicable	4
The total blocking time was 0.1 seconds. This measures the total amount of time that a page is blocked from responding to user input, such as mouse clicks, screen taps, or keyboard presses.	Passed	3
The total page size was 0.7 megabytes (MB). Excessively large page sizes can lead to long load times for visitors.	Passed	3
Unminified CSS was not detected. Minifying CSS files can reduce payload sizes.	Passed	3
Unminified JavaScript was not detected. Minifying JavaScript files can reduce payload sizes and script parse time.	Passed	3
Unused CSS rules were not detected. Reduce unused rules from stylesheets to decrease bytes consumed by network activity.	Passed	3
Some unused JavaScript was detected. Reduce unused JavaScript and defer loading scripts until they are required to decrease bytes consumed by network activity.	Warnings	2
Images are optimized. Optimized images load faster and consume less network resources.	Passed	3
Preconnects to required origins Add preconnect resource hints to establish early connections to important third-party origins.	Warnings	2
Preloading of resources Preloading of key resources can make your pages load faster.	Not applicable	4
Responsive images were detected. Responsive images that are appropriately-sized save network resources and improve load time.	Passed	3
Text compression was detected. Text-based resources can be served with compression (gzip, deflate or brotli) to minimize network load.	Passed	3

DESIGN

You have 2.7 seconds to grab the attention of your target audience. The best websites achieve this with a unique brand identity, strong visuals, and a clear message.

Design Grade

react.dev achieved a design grade of 91 out of 100 based on 16 design tests

Design Test Summary

Failed: 1

Warnings: 0

Passed: 11

Not Applicable: 4

Design Test Results

A properly defined charset was detected. Incorrect character encoding can result in garbled text and is properly declared in the charset attribute or the Content-Type HTTP response header.	Passed	3
Background and foreground colors do not appear to have a sufficient contrast ratio. Low-contrast text can be difficult or even impossible for many visitors to read.	Failed	1
Cumulative layout shift This measures unexpected page movements which visitors find annoying and can intefere with website functionality.	Not applicable	4
The doctype was specified. Specifying a doctype prevents the browser from switching to quirks mode, which can cause a website to render in unexpected ways.	Passed	3
Text remains visible during font loading. Ensure text is user-visible and avoid flashes of invisible text while webfonts are loading.	Passed	3
Legible font sizes Smaller font sizes can be difficult to read especially on mobile devices.	Not applicable	4
The user's location was not requested on page load. Users are mistrustful or confused by websites that request their location without context.	Passed	3
Images were displayed with the correct aspect ratio. Images displayed with an incorrect aspect ratio look distorted.	Passed	3
Responsive images were detected. Images should be responsive and proportional to the display size and the pixel ratio to maximize image clarity.	Passed	3
Meta refresh Users do not expect a page to refresh automatically as such refreshing can be disorienting.	Not applicable	4
Unload event listeners were not detected. Unload event listeners do not fire reliably and listening for them can intefere with website functionality and browser optimizations.	Passed	3
Notification permission was not requested on page load. Users are mistrustful of or confused by sites that request to send notifications without context.	Passed	3
Tap targets Interactive elements like buttons and links should be large enough and have enough space around them to be easy to tap without overlapping onto other elements.	Not applicable	4
Image elements have a defined width and height. Images should have an explicit width and height to reduce layout shifts.	Passed	3
Passive event listeners detected. Touch and wheel event listeners should be marked as passive to improve scroll performance.	Passed	3
The viewport was set with width or initial-scale. Correctly setting the viewport optimizes websites for mobile screen sizes and also prevents delays to user input.	Passed	3

SECURITY

A secure website protects both visitors and the website owner from hackers and cyber criminals who are continuously scanning for weak websites to attack.

Security Grade

react.dev achieved a security grade of 100 out of 100 based on 6 security tests

Security Test Summary

Failed: 0

Warnings: 0

Passed: 4

Not Applicable: 2

Security Test Results

Deprecated API calls were not detected. Deprecated APIs are scheduled to be removed from browsers and can introduce errors and vulnerabilities.	Passed	3
Console errors were not detected. Console errors indicate unresolved problems that can lead to security issues.	Passed	3
No inspector issues were detected. Inspector issues indicate unresolved problems which can include security issues.	Passed	3
The website uses HTTPS. All websites should be protected with HTTPS including ones that don't handle sensitive data.	Passed	3
Vulnerable JavaScript libraries Some third-party JavaScript libraries contain known security vulnerabilities that are easily identified and exploited by attackers.	Not applicable	4
Password fields Preventing password fields from being pasted into undermines good security policy.	Not applicable	4

ACCESSIBILITY

Many websites are developed with accessibility barriers that make them difficult or even impossible for visually impaired and other disabled visitors to use.

Accessibility Grade

react.dev achieved a accessibility grade of 93 out of 100 based on 38 accessibility tests

Accessibility Test Summary

Failed: 1

Warnings: 0

Passed: 14

Not Applicable: 23

Accessibility Test Results

Access key values Access keys let users quickly focus on or navigate to a part of the page and must be unique.	Not applicable	4
Definition lists When definition lists are not properly marked up screen readers may produce confusing or inaccurate output.	Not applicable	4
Definition list items Definition list items must be wrapped in a parent element to ensure that screen readers can properly announce them.	Not applicable	4
Unique focusable elements All focusable elements must have a unique id to ensure that they're visible to assistive technologies.	Not applicable	4
ARIA IDs are unique. The value of an ARIA ID must be unique to prevent other instances from being overlooked by assistive technologies.	Passed	3
Form field labels Form fields with multiple labels can be confusingly announced by assistive technologies like screen readers.	Not applicable	4
Frame element titles Screen reader users rely on frame titles to describe the contents of frames.	Not applicable	4
Heading elements do not appear in a sequentially descending order. Properly ordered headings that do not skip levels convey the semantic structure of the page making it easier to navigate and understand when using assistive technologies.	Failed	1
The HTML element has a lang attribute. If the website doesn't specify a language correctly screen readers might not be able to read the text correctly.	Passed	3
The HTML element has a valid lang attribute. Specifying a valid land attribute helps screen readers announce text correctly.	Passed	3
Image button alt attributes When an image is being used as a button providing alternative text can help screen reader users understand the purpose of the button.	Not applicable	4
Form elements have associated labels. Labels ensure that forms are announced properly by assistive technologies like screen readers.	Passed	3
Links have a discernible name. Link text that is discernible, unique, and focusable improves the navigation experience for screen reader users.	Passed	3
List elements Lists must only contain list elements so that screen readers can correctly announce lists.	Not applicable	4
List items List items must be contained within a parent list for screen readers to properly announce lists.	Not applicable	4
Zooming and scaling is allowed. Disabling zooming and scaling is problematic for users with low vision who rely on screen magnification to properly see the contents of a website.	Passed	3
Object elements alternate text Screen readers cannot translate non-text such as objects so alternate text should be provided for these elements. `\u003cobject\u003e` elements helps screen readers convey meaning to users.	Not applicable	4
Tabindex values A tabindex value greater than 0 implies an explicit navigation ordering which often creates frustrating experiences for users who rely on assistive technologies.	Not applicable	4
Table headers markup Screen readers have a specific way of announcing tables and when tables are not properly marked up, this creates the opportunity for confusing or inaccurate screen reader output.	Not applicable	4
Table header data cells When tables are not marked up semantically and do not have the correct header structure, screen reader users cannot correctly perceive the relationships between the cells and their contents visually.	Not applicable	4
Lang attributes Specifying a valid lang attributes ensure that text is pronounced correctly by a screen reader.	Not applicable	4
Video captions When a video provides a caption it is easier for deaf and hearing impaired users to access its information.	Not applicable	4

SEARCH

People search on Google every day to help them find whatever they are looking for, but are you doing the rights things to encourage Google to display your website in search results ahead of your competitors?

Search Score

react.dev achieved a search grade of 90 out of 100 based on 12 search tests

Search Test Summary

Failed: 1

Warnings: 0

Passed: 9

Not Applicable: 2

Search Test Results

Valid canonical links tell search engines which version of a page to crawl and display to users in search results.	Not applicable	4
Some links are not crawlable. Search engines use correctly formatted links to crawl websites.	Failed	1
A document title was detected. Search engine users rely on the document title to determine if a page is relevant to their search.	Passed	3
A valid hreflang was detected. Many sites provide different versions of a page based on a user's language or region and hreflang links tell search engines the URLs for all the versions of a page so that they can display the correct version.	Passed	3
A successful HTTP status code was detected. Pages with unsuccessful HTTP status codes may not be indexed by search engines properly.	Passed	3
All image elements have alt attributes. Images should have a descriptive alternate text which is meaningful for search engines and users.	Passed	3
The website is crawlable. Search engines are unable to include websites in search results if they don't have permission to crawl them.	Passed	3
Links have descriptive text. Descriptive link text helps search engines understand your content.	Passed	3
A meta description was detected. Meta descriptions may be included in search results to help convey website content.	Passed	3
Plugins were not detected. Search engines can't index plugin content and many devices restrict plugins or don't support them.	Passed	3
The robots.txt is valid. A valid robots.txt is required for search engines to understand how to crawl or index a website.	Passed	3
Structured data Search engines use structured data to understand what kind of content is on a website.	Not applicable	4

SOCIAL

Social platforms can help websites reach, connect, and share information with people who share similar passions or interests.

Social Grade

react.dev achieved a social grade of 30 out of 100 based on over 100 social factors

Facebook Page

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Open Graph

Open Graph is a protocol that is used to integrate any web page into the social graph.

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Twitter Account

A link to a Twitter Account helps visitors discover and interact with a website on Twitter.

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ADVERTISING

Online advertising platforms can help businesses and organisations find, reach, and engage with people who are likely to be interested in their products or services.

Advertising Grade

react.dev achieved an advertising grade of 0 out of 100 based on over 200 advertising factors

TECHNOLOGY

Choosing the right technology to power your website can often mean the difference between staying one step ahead of your competition or falling behind in the race to engage with customers online.

Technology Grade

react.dev achieved a technology grade of 21 out of 100 based on scanning for over 3,000 website technologies

Technology Test Results

	Description	Categories
HSTS	HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.	Security
Module Federation	Module Federation is a webpack technology for dynamically loading parts of other independently deployed builds.	Miscellaneous
Vercel		PaaS
webpack	Webpack is an open-source JavaScript module bundler.	Miscellaneous

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react.dev

Overall Grade

Speed

Design

Security

Accessibility

Search

Social

Advertising

Technology

SPEED

Speed Grade

Speed Test Summary

Speed Test Results

JavaScript execution took 0.5 seconds.

The size of the document object model was 1731 elements.

No duplicate Javascript was detected.

No inefficient animated content was detected.

The first contentful paint took 0.3 seconds.

The time to interactive was 0.9 seconds.

The largest contentful paint took 0.4 seconds.

Lazy loading of the largest contentful paint image

No legacy JavaScript was detected.

The main thread was busy for 1.1 seconds.

The first input delay was 0.1 seconds.

Modern image formats

Network server latency

Usage of document.write() was not detected.

Offscreen and hidden images were lazily loaded.

Preloading of optional fonts

The largest contentful paint image was preloaded.

Excessive page redirects were not detected.

Render blocking resources

The server response time was 0.1 seconds.

The speed index was 0.5 seconds.

Lazy loading of third party resources

The total blocking time was 0.1 seconds.

The total page size was 0.7 megabytes (MB).

Unminified CSS was not detected.

Unminified JavaScript was not detected.

Unused CSS rules were not detected.

Some unused JavaScript was detected.

Images are optimized.

Preconnects to required origins

Preloading of resources

Responsive images were detected.

Text compression was detected.

DESIGN

Design Grade

Design Test Summary

Design Test Results

A properly defined charset was detected.

Background and foreground colors do not appear to have a sufficient contrast ratio.

Cumulative layout shift

The doctype was specified.

Text remains visible during font loading.

Legible font sizes

The user's location was not requested on page load.

Images were displayed with the correct aspect ratio.

Responsive images were detected.

Meta refresh

Unload event listeners were not detected.

Notification permission was not requested on page load.

Tap targets

Image elements have a defined width and height.

Passive event listeners detected.

The viewport was set with width or initial-scale.

SECURITY

Security Grade

Security Test Summary

Security Test Results

Deprecated API calls were not detected.

Console errors were not detected.

No inspector issues were detected.

The website uses HTTPS.

Vulnerable JavaScript libraries

Password fields

ACCESSIBILITY

Accessibility Grade

Accessibility Test Summary