Acs.org Site Title
American Chemical Society
Acs.org Meta Description
ACS is one of the world’s largest scientific societies and the premier home of chemistry professionals. Find career opportunities, educational resources, and more.
Acs.org Test Results
Acs.org Mobile Performance: 11/100
Quick overview:
Opportunities
These suggestions can help your page load faster. They don't directly affect the Performance score.
Avoid multiple page redirects. Potential savings of 21,900 ms
Redirects introduce additional delays before the page can be loaded. Learn more.
Defer offscreen images. Potential savings of 417 KiB
Consider lazy-loading offscreen and hidden images after all critical resources have finished loading to lower time to interactive. Learn more.
Remove unused JavaScript. Potential savings of 383 KiB
Remove unused JavaScript to reduce bytes consumed by network activity. Learn more.
Serve images in next-gen formats. Potential savings of 178 KiB
Image formats like JPEG 2000, JPEG XR, and WebP often provide better compression than PNG or JPEG, which means faster downloads and less data consumption. Learn more.
Eliminate render-blocking resources. Potential savings of 1,640 ms
Resources are blocking the first paint of your page. Consider delivering critical JS/CSS inline and deferring all non-critical JS/styles. Learn more.
Minify JavaScript. Potential savings of 145 KiB
Minifying JavaScript files can reduce payload sizes and script parse time. Learn more.
Remove unused CSS. Potential savings of 80 KiB
Remove dead rules from stylesheets and defer the loading of CSS not used for above-the-fold content to reduce unnecessary bytes consumed by network activity. Learn more.
Efficiently encode images. Potential savings of 21 KiB
Optimized images load faster and consume less cellular data. Learn more.
Diagnostics
More information about the performance of your application. These numbers don't directly affect the Performance score.
Does not use passive listeners to improve scrolling performance
Consider marking your touch and wheel event listeners as `passive` to improve your page's scroll performance. Learn more.
Reduce the impact of third-party code
Third-party code blocked the main thread for 1,000 ms
Third-party code can significantly impact load performance. Limit the number of redundant third-party providers and try to load third-party code after your page has primarily finished loading. Learn more.
Ensure text remains visible during webfont load
Leverage the font-display CSS feature to ensure text is user-visible while webfonts are loading. Learn more.
Avoid `document.write()`
For users on slow connections, external scripts dynamically injected via `document.write()` can delay page load by tens of seconds. Learn more.
Serve static assets with an efficient cache policy
56 resources found
A long cache lifetime can speed up repeat visits to your page. Learn more.
Minimize main-thread work
8.7 s
Consider reducing the time spent parsing, compiling and executing JS. You may find delivering smaller JS payloads helps with this. Learn more
Reduce JavaScript execution time
5.5 s
Consider reducing the time spent parsing, compiling, and executing JS. You may find delivering smaller JS payloads helps with this. Learn more.
Avoid an excessive DOM size
1,032 elements
A large DOM will increase memory usage, cause longer style calculations, and produce costly layout reflows. Learn more.
Keep request counts low and transfer sizes small
148 requests • 2,111 KiB
To set budgets for the quantity and size of page resources, add a budget.json file. Learn more.
Avoid long main-thread tasks
20 long tasks found
Lists the longest tasks on the main thread, useful for identifying worst contributors to input delay. Learn more
Largest Contentful Paint element
1 element found
This is the largest contentful element painted within the viewport. Learn More
Avoid chaining critical requests
15 chains found
The Critical Request Chains below show you what resources are loaded with a high priority. Consider reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load. Learn more.
Avoid large layout shifts
5 elements found
These DOM elements contribute most to the CLS of the page.
Acs.org Mobile SEO: 72/100
Quick overview:
Content Best Practices
Format your HTML in a way that enables crawlers to better understand your app’s content.
Image elements do not have `[alt]` attributes
Informative elements should aim for short, descriptive alternate text. Decorative elements can be ignored with an empty alt attribute. Learn more.
Links do not have descriptive text
1 link found
Descriptive link text helps search engines understand your content. Learn more.
Mobile Friendly
Make sure your pages are mobile friendly so users don’t have to pinch or zoom in order to read the content pages. Learn more.
Tap targets are not sized appropriately
42% appropriately sized tap targets
Interactive elements like buttons and links should be large enough (48x48px), and have enough space around them, to be easy enough to tap without overlapping onto other elements. Learn more.
Crawling and Indexing
To appear in search results, crawlers need access to your app.
Links are not crawlable
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 More
Acs.org Mobile Best Practices: 69/100
Quick overview:
Trust and Safety
Includes front-end JavaScript libraries with known security vulnerabilities
6 vulnerabilities detected
Some third-party scripts may contain known security vulnerabilities that are easily identified and exploited by attackers. Learn more.
Does not use HTTPS
1 insecure request found
All sites should be protected with HTTPS, even ones that don't handle sensitive data. This includes avoiding mixed content, where some resources are loaded over HTTP despite the initial request being servedover HTTPS. HTTPS prevents intruders from tampering with or passively listening in on the communications between your app and your users, and is a prerequisite for HTTP/2 and many new web platform APIs. Learn more.
General
Uses deprecated APIs
1 warning found
Deprecated APIs will eventually be removed from the browser. Learn more.
User Experience
Serves images with low resolution
Image natural dimensions should be proportional to the display size and the pixel ratio to maximize image clarity. Learn more.
Acs.org Mobile Progressive Web App: 21/100
Quick overview:
PWA Optimized
Does not set a theme color for the address bar.
The browser address bar can be themed to match your site. Learn more. Failures: No manifest was fetched,
No `<meta name="theme-color">` tag found.
Manifest doesn't have a maskable icon
A maskable icon ensures that the image fills the entire shape without being letterboxed when installing the app on a device. Learn more. No manifest was fetched
Is not configured for a custom splash screen
A themed splash screen ensures a high-quality experience when users launch your app from their homescreens. Learn more. Failures: No manifest was fetched.
Does not provide a valid `apple-touch-icon`
For ideal appearance on iOS when users add a progressive web app to the home screen, define an `apple-touch-icon`. It must point to a non-transparent 192px (or 180px) square PNG. Learn More.
Fast and reliable
Current page does not respond with a 200 when offline
If you're building a Progressive Web App, consider using a service worker so that your app can work offline. Learn more.
Page load is not fast enough on mobile networks
Interactive at 18.7 s
A fast page load over a cellular network ensures a good mobile user experience. Learn more. Your page loads too slowly and is not interactive within 10 seconds. Look at the opportunities and diagnostics in the "Performance" section to learn how to improve.
`start_url` does not respond with a 200 when offline
A service worker enables your web app to be reliable in unpredictable network conditions. Learn more. No usable web app manifest found on page.
Installable
Does not register a service worker that controls page and `start_url`
The service worker is the technology that enables your app to use many Progressive Web App features, such as offline, add to homescreen, and push notifications. Learn more.
Web app manifest does not meet the installability requirements
Browsers can proactively prompt users to add your app to their homescreen, which can lead to higher engagement. Learn more. Failures: No manifest was fetched.
Does not use HTTPS
1 insecure request found
All sites should be protected with HTTPS, even ones that don't handle sensitive data. This includes avoiding mixed content, where some resources are loaded over HTTP despite the initial request being servedover HTTPS. HTTPS prevents intruders from tampering with or passively listening in on the communications between your app and your users, and is a prerequisite for HTTP/2 and many new web platform APIs. Learn more.
Acs.org Mobile Accessibility: 66/100
Quick overview:
Names and labels
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.
Image elements do not have `[alt]` attributes
Informative elements should aim for short, descriptive alternate text. Decorative elements can be ignored with an empty alt attribute. Learn more.
Links do not have a discernible name
Link text (and alternate text for images, when used as links) that is discernible, unique, and focusable improves the navigation experience for screen reader users. Learn more.
Form elements do not have associated labels
Labels ensure that form controls are announced properly by assistive technologies, like screen readers. Learn more.
Buttons do not have an accessible name
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 more.
ARIA
These are opportunities to improve the usage of ARIA in your application which may enhance the experience for users of assistive technology, like a screen reader.
`[aria-*]` attributes do not have valid values
Assistive technologies, like screen readers, can't interpret ARIA attributes with invalid values. Learn more.
ARIA IDs are not unique
The value of an ARIA ID must be unique to prevent other instances from being overlooked by assistive technologies. Learn more.
Navigation
These are opportunities to improve keyboard navigation in your application.
Heading elements are not 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. Learn more.
Contrast
These are opportunities to improve the legibility of your content.
Background and foreground colors do not have a sufficient contrast ratio.
Low-contrast text is difficult or impossible for many users to read. Learn more.
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