User Experience Performance Single Region Diagnostic Results

Webpage: http://tuandat.com.vn

Device: Desktop Computer

Region: Japan (Tokyo)

Single Region Score

52
Page Performance Needs Improvement
A total of 25 improvements can achieve a higher score
Efficiently encode images

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

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].

Avoid multiple page redirects

Redirects introduce additional delays before the page can be loaded. [Learn how to avoid page redirects].

Reduce initial server response time

Keep the server response time for the main document short because all other requests depend on it. [Learn more about the Time to First Byte metric].

Reduce the impact of third-party code

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 how to minimize third-party impact].

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

Screen readers require list items (`

  • `) to be contained within a parent `
    • Does not redirect HTTP traffic to HTTPS

    Make sure that you redirect all HTTP traffic to HTTPS in order to enable secure web features for all your users. [Learn more].

    Properly size images

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

    Does not use HTTPS

    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 served over 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 about HTTPS].

    Displays images with incorrect aspect ratio

    Image display dimensions should match natural aspect ratio. [Learn more about image aspect ratio].

    Largest Contentful Paint element

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

    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].

    Select elements do not have associated label elements.

    Form elements without effective labels can create frustrating experiences for screen reader users. [Learn more about the `select` element].

    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 how to make links accessible].

    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].

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

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

    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].

    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].

    Uses third-party cookies

    Chrome is moving towards a new experience that allows users to choose to browse without third-party cookies. [Learn more about third-party cookies].

    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].

    Some third-party resources can be lazy loaded with a facade

    Some third-party embeds can be lazy loaded. Consider replacing them with a facade until they are required. [Learn how to defer third-parties with a facade].

    `[user-scalable="no"]` is used in the `<meta name="viewport">` element or the `[maximum-scale]` attribute is less than 5.

    Disabling zooming is problematic for users with low vision who rely on screen magnification to properly see the contents of a web page. [Learn more about the viewport meta tag].

    Issues were logged in the `Issues` panel in Chrome Devtools

    Issues logged to the `Issues` panel in Chrome Devtools indicate unresolved problems. They can come from network request failures, insufficient security controls, and other browser concerns. Open up the Issues panel in Chrome DevTools for more details on each issue.

    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]

    ARIA input fields do not have accessible names

    When an input field doesn't have an accessible name, screen readers announce it with a generic name, making it unusable for users who rely on screen readers. [Learn more about input field labels].

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