User Experience Performance Single Region Diagnostic Results

Webpage: https://investor.gm.com

Device: Desktop Computer

Region: United States East (Virginia)

Single Region Score

50
Page Performance Needs Improvement
A total of 24 improvements can achieve a higher score
Elements with an ARIA `[role]` that require children to contain a specific `[role]` are missing some or all of those required children.

Some ARIA parent roles must contain specific child roles to perform their intended accessibility functions. [Learn more about roles and required children elements].

Avoid serving legacy JavaScript to modern browsers

Polyfills and transforms enable legacy browsers to use new JavaScript features. However, many aren't necessary for modern browsers. For your bundled JavaScript, adopt a modern script deployment strategy using [module/nomodule feature detection] to reduce the amount of code shipped to modern browsers, while retaining support for legacy browsers. [Learn how to serve modern JavaScript]

Missing source maps for large first-party JavaScript

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].

List items (`<li>`) are not contained within `<ul>`, `<ol>` or `<menu>` parent elements.

Screen readers require list items (`

  • `) to be contained within a parent `
    • 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 about the `alt` attribute].

    Layout shift culprits

    Layout shifts occur when elements move absent any user interaction. [Investigate the causes of layout shifts], such as elements being added, removed, or their fonts changing as the page loads.

    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 how to make buttons more accessible].

    Serve images in next-gen formats

    Image formats like WebP and AVIF often provide better compression than PNG or JPEG, which means faster downloads and less data consumption. [Learn more about modern image formats].

    Eliminate render-blocking resources

    Resources are blocking the first paint of your page. Consider delivering critical JS/CSS inline and deferring all non-critical JS/styles. [Learn how to eliminate render-blocking resources].

    Largest Contentful Paint element

    This is the largest contentful element painted within the viewport. [Learn more about the Largest Contentful Paint element]

    Reduce unused CSS

    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].

    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 about heading order].

    LCP request discovery

    Optimize LCP by making the LCP image [discoverable] from the HTML immediately, and [avoiding lazy-loading]

    Skip links are not focusable.

    Including a skip link can help users skip to the main content to save time. [Learn more about skip links].

    Third parties

    Third party code can significantly impact load performance. [Reduce and defer loading of third party code] to prioritize your page's content.

    `[role]`s are not contained by their required parent element

    Some ARIA child roles must be contained by specific parent roles to properly perform their intended accessibility functions. [Learn more about ARIA roles and required parent element].

    Efficiently encode images

    Optimized images load faster and consume less cellular data. [Learn how to efficiently encode images].

    Browser errors were logged to the console

    Errors logged to the console indicate unresolved problems. They can come from network request failures and other browser concerns. [Learn more about this errors in console diagnostic audit]

    Avoid large layout shifts

    These are the largest layout shifts observed on the page. Each table item represents a single layout shift, and shows the element that shifted the most. Below each item are possible root causes that led to the layout shift. Some of these layout shifts may not be included in the CLS metric value due to [windowing]. [Learn how to improve CLS]

    Reduce unused JavaScript

    Reduce unused JavaScript and defer loading scripts until they are required to decrease bytes consumed by network activity. [Learn how to reduce unused JavaScript].

    Links do not have descriptive text

    Descriptive link text helps search engines understand your content. [Learn how to make links more accessible].

    Properly size images

    Serve images that are appropriately-sized to save cellular data and improve load time. [Learn how to size images].

    Minify CSS

    Minifying CSS files can reduce network payload sizes. [Learn how to minify CSS].

    `[aria-hidden="true"]` elements contain focusable descendents

    Focusable descendents within an `[aria-hidden="true"]` element prevent those interactive elements from being available to users of assistive technologies like screen readers. [Learn how `aria-hidden` affects focusable elements].

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