Jb51.net 脚本之家_www.jb51.net
脚本之家是国内专业的网站建设资源、脚本编程学习类网站，提供asp、php、asp.net、javascript、jquery、vbscript、dos批处理、网页制作、网络编程、网站建设等编程资料。
jb51.net Desktop Performance
67/100
These metrics represent real-world Chrome users experience viewing jb51.net web page. Reports are focused on loading performance and other critical factors that most affect user experience. Follow our guide to track, optimize, and improve the quality of your web pages.
User Loading Experience
Cumulative Layout Shift
First Input Delay
First Contentful Paint
Largest Contentful Paint
Metrics
Cumulative Layout Shift17/100 0.491
Cumulative Layout Shift measures the movement of visible elements within the viewport. Learn more.
Speed Index18/100 3.4 s
Speed Index shows how quickly the contents of a page are visibly populated. Learn more.
Largest Contentful Paint39/100 2.8 s
Largest Contentful Paint marks the time at which the largest text or image is painted. Learn More
First Contentful Paint90/100 0.9 s
First Contentful Paint marks the time at which the first text or image is painted. Learn more.
Time to Interactive100/100 1.3 s
Time to interactive is the amount of time it takes for the page to become fully interactive. Learn more.
Total Blocking Time100/100 20 ms
Sum of all time periods between FCP and Time to Interactive, when task length exceeded 50ms, expressed in milliseconds. Learn more.
Should Fix (17)
Opportunities
These suggestions can help your page load faster. They don't directly affect the Performance score.
Properly size images
Potential savings of 2,871 KiB
2,520 ms
Serve images in next-gen formats
Potential savings of 2,098 KiB
1,960 ms
Efficiently encode images
Potential savings of 1,045 KiB
1,020 ms
Reduce initial server response time
Root document took 1,550 ms
952 ms
Use video formats for animated content
Potential savings of 926 KiB
780 ms
Defer offscreen images
Potential savings of 57 KiB
100 ms
Eliminate render-blocking resources
Potential savings of 80 ms
77 ms
Diagnostics
More information about the performance of your application. These numbers don't directly affect the Performance score.
Serve static assets with an efficient cache policy
100 resources found
Avoid `document.write()`
Avoid enormous network payloads
Total size was 5,165 KiB
Avoid an excessive DOM size
1,746 elements
Minimizes main-thread work
1.7 s
Keep request counts low and transfer sizes small
105 requests • 5,165 KiB
Avoid long main-thread tasks
3 long tasks found
Avoid large layout shifts
5 elements found
Largest Contentful Paint element
1 element found
Avoid chaining critical requests
9 chains found
Passed Audits (12)
Remove unused JavaScript
Remove unused CSS
Preload key requests
Minify JavaScript
Potential savings of 12 KiB
Uses passive listeners to improve scrolling performance
Avoid multiple page redirects
Potential savings of 190 ms
Preconnect to required origins
Minimize third-party usage
Third-party code blocked the main thread for 0 ms
Minify CSS
All text remains visible during webfont loads
Enable text compression
Potential savings of 24 KiB
JavaScript execution time
0.2 s
jb51.net Desktop SEO
73/100
These checks ensure that your page is optimized for search engine results ranking. There are additional factors Lighthouse does not check that may affect your search ranking. Learn more. Run these additional validators on your site to check additional SEO best practices.
Should Fix (3)
Crawling and Indexing
To appear in search results, crawlers need access to your app.
robots.txt is not valid
1 error found
Links are not crawlable
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
Passed Audits (8)
Page isn’t blocked from indexing
Document has a valid `hreflang`
Document has a meta description
Links have descriptive text
Has a `<meta name="viewport">` tag with `width` or `initial-scale`
Page has successful HTTP status code
Document has a `<title>` element
Document avoids plugins
jb51.net Desktop Best Practices
69/100
These checks highlight opportunities to improve the overall code health of jb51.net page. Current recommendations will help to make your page fast and secure, to create a good user experience and to avoid deprecated technologies.
Should Fix (4)
Trust and Safety
Does not use HTTPS
3 insecure requests found
Includes front-end JavaScript libraries with known security vulnerabilities
4 vulnerabilities detected
Links to cross-origin destinations are unsafe
User Experience
Displays images with incorrect aspect ratio
Passed Audits (10)
Avoids Application Cache
Avoids requesting the geolocation permission on page load
Avoids deprecated APIs
Serves images with appropriate resolution
No browser errors logged to the console
Page has the HTML doctype
Avoids requesting the notification permission on page load
Allows users to paste into password fields
Detected JavaScript libraries
Properly defines charset
jb51.net Desktop Progressive Web App
19/100
These checks validate the aspects of a Progressive Web App. Learn more. These checks are required by the baseline PWA Checklist but are not automatically checked by Lighthouse. They do not affect your score but it's important that you verify them manually.
Should Fix (10)
Installable
Web app manifest does not meet the installability requirements
Does not use HTTPS
3 insecure requests found
Does not register a service worker that controls page and `start_url`
Fast and reliable
Page load is not fast enough on mobile networks
Interactive on simulated mobile network at 15.3 s
Current page does not respond with a 200 when offline
`start_url` does not respond with a 200 when offline
PWA Optimized
Manifest doesn't have a maskable icon
Does not set a theme color for the address bar.
Is not configured for a custom splash screen
Does not provide a valid `apple-touch-icon`
Passed Audits (3)
Contains some content when JavaScript is not available
Has a `<meta name="viewport">` tag with `width` or `initial-scale`
Redirects HTTP traffic to HTTPS
jb51.net Desktop Accessibility
57/100
These checks highlight opportunities to improve the accessibility of your web app. Only a subset of accessibility issues can be automatically detected so manual testing is also encouraged. These items address areas which an automated testing tool cannot cover. Learn more in our guide on conducting an accessibility review.
Should Fix (5)
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.
Form elements do not have associated labels
Image elements do not have `[alt]` attributes
Links do not have a discernible name
Internationalization and localization
These are opportunities to improve the interpretation of your content by users in different locales.
`<html>` element does not have a `[lang]` attribute
Contrast
These are opportunities to improve the legibility of your content.
Background and foreground colors do not have a sufficient contrast ratio.
Passed Audits (8)
`[user-scalable="no"]` is not used in the `<meta name="viewport">` element and the `[maximum-scale]` attribute is not less than 5.
`[id]` attributes on active, focusable elements are unique
`[aria-hidden="true"]` is not present on the document `<body>`
The page contains a heading, skip link, or landmark region
Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`).
No element has a `[tabindex]` value greater than 0
List items (`<li>`) are contained within `<ul>` or `<ol>` parent elements
Document has a `<title>` element
Desktop Speed
60/100
These checks analyze the performance of jb51.net on desktop devices and return PageSpeed score and information on how to improve the load time. What makes a good Progressive Web App?
Should Fix (7)
Leverage browser caching
Enable compression
Eliminate render-blocking JavaScript and CSS in above-the-fold content
Optimize images
Prioritize visible content
Minify JavaScript
Minify CSS
Passed Audits (3)
Avoid landing page redirects
Reduce server response time
Minify HTML
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