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CN · CNY (¥) · Estimated Applicable regulations: PIPL Dev cost: ¥350/hr How jurisdiction is detected

URL substituted: You submitted https://pku.edu.cn but we scanned https://www.pku.edu.cn instead — the HTTPS certificate on the submitted hostname didn't cover that name, so we retried on the www. variant

Spain Spain · Madrid Completed: Apr 21, 2026 20:34 UTC
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Mobile 375 × 812

Screenshot of the audited page (Mobile 375×812)

Desktop 1440 × 900

Screenshot of the audited page (Desktop 1440×900)
D69

Site Health

Score: 69 / 100

Based on 8 categories, 0 sections

Decent speed, but optimizing further could improve engagement.

Several missing protections leave your users and data exposed.

Major barriers for users with disabilities — up to 15% of your audience.

Well-optimized for search — your content is discoverable.

Solid infrastructure — fast server responses across the board.

Several regulatory requirements are not yet met.

Missing metadata means poor previews on social media and search.

Heavier than average — reducing page weight saves energy and bandwidth.

How is this calculated?

The overall score is a weighted average of individual category scores. Categories with more impact on user experience and security carry more weight.

Performance 25%Security 25%Accessibility 15%SEO 10%Infrastructure 10%Compliance 8%Content 5%Sustainability 2%

Weights reflect general web best practices. Individual needs may differ.

How the composite score is calculated

How you compare

HSTS · 1596 peers
You 69
·
Avg 74
At average
0 50 100
Better than 4% of HSTS sites See full HSTS benchmark →
jQuery · 1027 peers
You 69
·
Avg 73
At average
0 50 100
Better than 6% of jQuery sites See full jQuery benchmark →

Top Priorities (5)

1

Content-Security-Policy header is missing

Security gaps expose your site and users to attacks, eroding trust.

Security › Security Headers
2

No Content-Security-Policy header found

Security gaps expose your site and users to attacks, eroding trust.

Security › Content Security Policy
3

Page weighs 24.5 MB (23.9 MB transferred)

Performance issues directly impact user engagement and conversion rates.

Performance › Page Weight Budget
4

1 control(s) without accessible label

Accessibility issues exclude users with disabilities — up to 15% of your potential audience.

Accessibility › Form Accessibility
5

1 image(s) missing alt attribute

Accessibility issues exclude users with disabilities — up to 15% of your potential audience.

Accessibility › Alt Text Quality
View fix priority matrix

Fix Priority Matrix

5 findings

Quick Wins

2

High impact, low effort — start here.

Strategic

3

High impact, requires investment.

Easy Improvements

0

Small gains, minimal effort.

Nothing in this quadrant — good news.

Deprioritize

0

Low impact, high effort — do last.

Nothing in this quadrant — good news.

← Low effort High effort →
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What fixing these means

Your site has several issues that may be affecting user experience and business outcomes. Your LCP of 30.4s exceeds Google's 2.5s 'Good' threshold and the 1 performance issue below directly contributes to it. Accessibility issues exclude users who rely on assistive technology — an estimated 15% of your potential audience. Addressing the critical issues below would have the most immediate impact on your user trust.

2 security gaps detected — browsers may warn visitors about your site.
Your LCP is 30.4s — fixing the 1 performance critical could bring it under Google's 2.5s 'Good' threshold.
2 accessibility issues exclude users who rely on assistive technology.
C
Could reach Estimate based on resolving critical issues

Conversion Barriers

2 critical 9 warning

11 barrier(s) likely increasing bounce by ~33%.

Speed (1)

Page takes 30.4s to load

+12% bounce

Users abandon at ~3s — you're 27.9s over the 2.5s threshold

Fix: Optimize render-blocking resources, preload the hero image, and compress images

Trust (2)

No HSTS header

+1% bounce

Returning visitors are briefly exposed to downgrade attacks on first request

Fix: Set Strict-Transport-Security: max-age=31536000; includeSubDomains

No Content-Security-Policy header

+1% bounce

Higher XSS blast radius — one compromised script can exfiltrate the checkout form

Fix: Ship a reporting-only CSP first, then enforce once violations are clean

Usability (3)

Layout shifts during page load

+3% bounce

Content movement causes mis-clicks on CTAs and form fields

Fix: Add width/height to images; reserve space for late-loading embeds

1 form field(s) without a label

+2% bounce

Screen readers skip unlabeled fields; autofill can't identify them; checkout abandonment spikes

Fix: Associate every input with a visible <label for="…">; add autocomplete attributes

Viewport disables user zoom

+2% bounce

Visitors with low vision can't read the page — and some jurisdictions treat this as a legal risk

Fix: Remove user-scalable=no; drop maximum-scale if it's below 2

Content (2)

No Open Graph tags

+2% bounce

Links shared on LinkedIn / Slack / Facebook show bare URLs — referral clicks drop

Fix: Add og:title, og:description, og:image, og:url to the page head

No structured data

+2% bounce

No rich-result eligibility in Google — lower SERP CTR vs competitors with stars and prices

Fix: Add JSON-LD for your page type (Product, Article, FAQPage, LocalBusiness, …)

Navigation (3)

73 link(s) with generic text ("click here", "read more")

+1% bounce

Screen-reader users navigating by link list see no context — and search engines can't infer relevance

Fix: Rewrite with descriptive phrases that identify the destination

No skip-to-content link

+1% bounce

Keyboard and screen-reader users must tab through the entire header on every page

Fix: Add a visible-on-focus <a href="#main">Skip to content</a> as the first focusable element

4 broken link(s) on the page

+5% bounce

Clicks land on 404s — trust drops and the session often ends

Fix: Fix or remove the broken destinations surfaced on the Content tab

Preliminary CRO audit — each barrier links to the tab with detailed analysis.

Return on Investment

¥2,100 investment → ¥43/month returns + CNY 50,000,000 risk avoided

Payback period: > 2 years First-year ROI: -75%

Investment

¥2,100

6h · 5 findings

Monthly returns

¥43 /mo

~¥516 / year

  • Bandwidth savings ¥43

Regulatory risk avoided

CNY 50,000,000

if kept compliant

  • PIPL CNY 50,000,000

¥350 — in quick wins — start here for the fastest payback

Figures combine localized regulatory fine ceilings, search/conversion value priced against local CPC, and bandwidth waste estimates. Results depend on implementation quality and audience composition. Not legal or financial advice.

Full methodology & sources

Estimated Remediation Cost

¥2,100

6.0 developer hours at ¥350/hr

Based on China rates (¥350/hr)

Quick wins
¥350 2 fixes in ~60 minutes

Start here for the best return on investment

Cost by category

Cost by effort level

Adjust assumptions
¥ /hr

Rates reflect fully-loaded developer cost including overhead

How developer rates are sourced

What Inaction Is Costing You

¥4,166,710 / month at risk

~¥50,000,516 / year if left unfixed

Compliance Risk

¥50,000,000

PIPL
  • No privacy policy link detected
    PIPL: CNY 100,000 – CNY 50,000,000
  • Privacy Policy not detected
    PIPL: CNY 100,000 – CNY 50,000,000

Bandwidth Waste

¥43 /mo

75250.5 MB/mo × 0.571 CNY/GB

  • Optimize transfer: save ~7.5 MB per page load
    Saves ¥43/mo

Compliance figures represent the statutory maximum fine for the most severe triggered category, capped per regulation — not the sum of per-finding penalties. Based on published regulatory fine ranges. This is not legal advice.

Compliance methodology · SEO assumptions · Bandwidth model

Your performance is already good — improvements may show diminishing returns

Unique monthly visitors from your analytics

Purchases, signups, or key actions

Optional — for revenue estimation

additional conversions/month

more engaged visitors from reduced bounce

potential monthly revenue
Current bounce (est.)
After fixes (est.)
Estimated bounce reduction

Fix 5 critical issues to capture this value

How this is calculated

Based on Google/Deloitte research ("Milliseconds Make Millions") showing a ~7% bounce rate increase per additional second of LCP above the 2.5s "Good" threshold.

Your site's LCP: → estimated after fixes.

These are estimates based on industry research — actual results vary

Bounce-rate model & assumptions

Your data stays in your browser — nothing is sent to our servers

Was this report useful?

Thanks for your feedback!

We'll use a cached audit if available, or offer to scan.

Checking for existing audit...

Lighthouse Scores

Industry-standard audits powered by Google Lighthouse.

55
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
69
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
100
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
82
SEO Measures basic SEO optimizations: meta tags, crawlability, link text, and mobile friendliness.

Core Web Vitals

Key metrics that affect user experience.

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

2.59 s

Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.

30.44 s

Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.

65 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.153

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

21.67 s

Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.

30.44 s

Detailed Report

Audit breakdown by category with detailed findings.

55

Performance

Insights

Remove large, duplicate JavaScript modules from bundles to reduce unnecessary bytes consumed by network activity.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Polyfills and transforms enable older browsers to use new JavaScript features. However, many aren't necessary for modern browsers. Consider modifying your JavaScript build process to not transpile Baseline features, unless you know you must support older browsers. Learn why most sites can deploy ES6+ code without transpiling

Why this matters

Shipping ES5 transpiled code to modern browsers wastes bytes — every user with an evergreen browser pays for compatibility you don't need.

Learn more ▾

Most users today run browsers that natively support ES6+, async/await, optional chaining, and the rest of modern JavaScript. Transpiling to ES5 'just in case' adds 20-40% to your bundle for no benefit. Configure your build to target a modern browserslist, or ship a differential bundle pair (modern + legacy) with the module/nomodule pattern.

Source: Google web.dev / Lighthouse

3rd party code can significantly impact load performance. Reduce and defer loading of 3rd party code to prioritize your page's content.

Why this matters

Performance issues directly impact user engagement and conversion rates.

A long cache lifetime can speed up repeat visits to your page. Learn more about caching.

Why this matters

Performance issues directly impact user engagement and conversion rates.

RequestCache TTLTransfer Size
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d1418721.jpg0.0 ms4.1 MiB
www.pku.edu.cn/dat/img/fe7afc17eccc47c499adca9b6c549b4e.jpg0.0 ms2.1 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/02/s69cdfe602790e.jpg0.0 ms2.1 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/17/s69e1c2a2f1019.jpg0.0 ms2.0 MiB
www.pku.edu.cn/dat/img/b2080858ec064a049de34c1ca7eb81e9.png0.0 ms1.9 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/09/s69d759af9ca1b.jpg0.0 ms1.4 MiB
www.pku.edu.cn/Uploads/Picture/2026/02/27/s69a0fec9dcf3b.jpg0.0 ms1.3 MiB
www.pku.edu.cn/dat/img/344b546ab3de42e885101859f6b8ed3b.jpg0.0 ms1.2 MiB
www.pku.edu.cn/Uploads/Picture/2025/09/17/s68ca4cd3c10bb.png0.0 ms697.4 KiB
www.pku.edu.cn/Uploads/Picture/2025/09/22/s68d10dcacb977.jpg0.0 ms567.5 KiB
www.pku.edu.cn/Uploads/Picture/2022/11/02/s6362348db2897.png0.0 ms543.5 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/31/s5e0aa9359ae68.png0.0 ms528.9 KiB
www.pku.edu.cn/Uploads/Picture/2022/11/22/s637cb8c134d80.jpg0.0 ms312.4 KiB
www.pku.edu.cn/Uploads/Picture/2024/11/06/s672b1d5a8248e.jpg0.0 ms232.3 KiB
www.pku.edu.cn/dat/img/3f24a9b3793f4520ae77c2d405badf92.jpg0.0 ms209.0 KiB
www.pku.edu.cn/dat/img/6c7b130555df477791adf7fa0d08e4bf.jpg0.0 ms178.0 KiB
www.pku.edu.cn/dat/img/85d41f2c3212461b885294a7d7d996b3.jpeg0.0 ms166.9 KiB
www.pku.edu.cn/dat/img/15e75d5f2c624be9a8cf1374c317fcf4.jpeg0.0 ms158.7 KiB
www.pku.edu.cn/dat/img/4bdf82f5e8a24fcc9b4e108f570f317a.jpeg0.0 ms155.7 KiB
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c77d7a66e70.jpg0.0 ms144.7 KiB
www.pku.edu.cn/Public/static/themes/image/pic65.jpg0.0 ms132.5 KiB
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c789787fad6.jpg0.0 ms125.3 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04176fbbfa3.png0.0 ms50.5 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/20/s5dfc40dc928fb.jpg0.0 ms47.4 KiB
www.pku.edu.cn/Public/static/themes/image/png92.png0.0 ms44.0 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/27/s5e05ab4267239.jpg0.0 ms41.4 KiB
www.pku.edu.cn/Public/static/themes/css/fonts/iconfont.woff0.0 ms39.9 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.js0.0 ms33.1 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04147ee4a83.png0.0 ms28.6 KiB
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6ab0f45e.jpg0.0 ms27.2 KiB
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6392fd51.jpg0.0 ms23.8 KiB
www.pku.edu.cn/Public/static/themes/css/global.css0.0 ms22.8 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.mCustomScrollbar.js0.0 ms22.2 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/05/s5de8762313bab.png0.0 ms18.0 KiB
www.pku.edu.cn/Public/static/themes/js/slick.js0.0 ms15.7 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58ada3ef15.jpg0.0 ms14.7 KiB
www.pku.edu.cn/Public/static/themes/js/iscroll.js0.0 ms12.8 KiB
www.pku.edu.cn/Public/static/themes/css/fix.css0.0 ms11.0 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58b3611072.jpg0.0 ms10.3 KiB
www.pku.edu.cn/Public/static/themes/image/png27.png0.0 ms9.5 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58bbebf671.jpg0.0 ms9.0 KiB
www.pku.edu.cn/Public/static/themes/js/plus/vivus.js0.0 ms8.7 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/18/s5dfa063869f70.jpg0.0 ms7.8 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58b7aaab99.jpg0.0 ms7.1 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/08/s5decd8b95f388.png0.0 ms6.7 KiB
www.pku.edu.cn/Public/static/themes/js/fun.js0.0 ms5.9 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/18/s5dfa062371400.jpg0.0 ms5.0 KiB
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mScroll.js0.0 ms4.8 KiB
www.pku.edu.cn/Public/static/themes/image/png25.png0.0 ms4.4 KiB
/collector/statistic.js?channelId=&channelName=&articleId...0.0 ms3.5 KiB
www.pku.edu.cn/Public/static/themes/image/png26.png0.0 ms2.9 KiB
www.pku.edu.cn/Public/static/themes/js/global.js0.0 ms2.8 KiB
www.pku.edu.cn/Public/static/themes/css/jquery.mCustomScrollbar.css0.0 ms2.7 KiB
www.pku.edu.cn/Public/static/themes/image/png23.png0.0 ms2.4 KiB
www.pku.edu.cn/Public/static/themes/js/homeJson.js0.0 ms2.2 KiB
www.pku.edu.cn/Public/static/themes/js/plus/jquery.imgpreload.js0.0 ms2.0 KiB
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mChange.js0.0 ms1.8 KiB
www.pku.edu.cn/Public/static/themes/image/png5.png0.0 ms1.7 KiB
www.pku.edu.cn/Public/static/themes/js/plus/old/winscreen.js0.0 ms1.7 KiB
www.pku.edu.cn/Public/static/themes/image/png32.svg0.0 ms1.3 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.easing.js0.0 ms1.2 KiB
www.pku.edu.cn/Public/static/themes/image/more1b.svg0.0 ms1.2 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.mousewheel.js0.0 ms1.1 KiB
www.pku.edu.cn/Public/static/themes/css/slick.css0.0 ms848 B
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d26ba8a5.jpg0.0 ms0 B
www.pku.edu.cn/dat/img/7fc4f699f7bc45f39f49c2d2d292bc1c.jpg0.0 ms0 B

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.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:node label:Element subItemsHeading:map[key:extra] valueType:node] map[granularity:0.001 key:score label:Layout shift score subItemsHeading:map[key:cause valueType:text] valueType:numeric]]
items: [map[node:map[type:text value:Total] score:0.152955] map[node:map[boundingRect:map[bottom:1190 height:406 left:18 right:394 top:785 width:376] lhId:page-20-DIV nodeLabel:北京大学第五届海军文化节举行 马来西亚拉曼大学校长访问北京大学 韩国友好人士代表团访问北京大学 中俄数学挑战基金研讨会在北京大学举行 2026北京大学管理质效年 path:2,HTML,1,BODY,8,DIV,1,DIV,0,DIV,0,DIV,1,DIV,1,DIV selector:div.home5 > div.block > div.content > div.list snippet:<div class="list"> type:node] score:0.152955]]

Consider setting font-display to swap or optional to ensure text is consistently visible. swap can be further optimized to mitigate layout shifts with font metric overrides.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLEst Savings
www.pku.edu.cn/Public/static/themes/css/fonts/iconfont.woff315 ms

Reducing the download time of images can improve the perceived load time of the page and LCP. Learn more about optimizing image size

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLResource SizeEst Savings
我国科学家近日在光通信和6G领域取得突破性进展 div.slick-track > div.slick-slide > div > div.child
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d1418721.jpg4.1 MiB2.8 MiB
div.block > div.list > div.item > div.pic div.block > div.list > div.item > div.pic
www.pku.edu.cn/dat/img/b2080858ec064a049de34c1ca7eb81e9.png1.9 MiB1.8 MiB
div.block > div.list > div.item > div.pic div.block > div.list > div.item > div.pic
www.pku.edu.cn/dat/img/344b546ab3de42e885101859f6b8ed3b.jpg1.2 MiB1.1 MiB
北京大学区域与国别研究院建院八周年 div.slick-track > div.slick-slide > div > div.child
www.pku.edu.cn/Uploads/Picture/2026/04/09/s69d759af9ca1b.jpg1.4 MiB1.1 MiB
全球首个靶向整合素的创新核药获批上市 北大为中国核医学70周年献礼 div.slick-track > div.slick-slide > div > div.child
www.pku.edu.cn/Uploads/Picture/2026/04/02/s69cdfe602790e.jpg2.1 MiB820.5 KiB
北京大学校园开放日暨本科招生宣讲会 div.slick-track > div.slick-slide > div > div.child
www.pku.edu.cn/Uploads/Picture/2026/04/17/s69e1c2a2f1019.jpg2.0 MiB747.5 KiB
体育与健康 div.home7 > div.block > div.d2 > div#d2
www.pku.edu.cn/Uploads/Picture/2025/09/17/s68ca4cd3c10bb.png697.2 KiB609.8 KiB
div.ptbox > div.inner > div.pic > div.img div.ptbox > div.inner > div.pic > div.img
www.pku.edu.cn/dat/img/fe7afc17eccc47c499adca9b6c549b4e.jpg2.1 MiB258.2 KiB
div.block > div.list > div.item > div.pic div.block > div.list > div.item > div.pic
www.pku.edu.cn/dat/img/3f24a9b3793f4520ae77c2d405badf92.jpg208.7 KiB181.2 KiB
div.inner > div.l > a > img div.inner > div.l > a > img
www.pku.edu.cn/dat/img/85d41f2c3212461b885294a7d7d996b3.jpeg166.7 KiB161.7 KiB
div.block > div.list > div.item > div.pic div.block > div.list > div.item > div.pic
www.pku.edu.cn/dat/img/6c7b130555df477791adf7fa0d08e4bf.jpg177.7 KiB148.9 KiB
div.pic > div.img > a > img div.pic > div.img > a > img
www.pku.edu.cn/dat/img/15e75d5f2c624be9a8cf1374c317fcf4.jpeg158.4 KiB139.8 KiB
div.inner > div.l > a > img div.inner > div.l > a > img
www.pku.edu.cn/Public/static/themes/image/pic65.jpg132.3 KiB127.8 KiB
div.pic > div.img > a > img div.pic > div.img > a > img
www.pku.edu.cn/dat/img/4bdf82f5e8a24fcc9b4e108f570f317a.jpeg155.4 KiB108.4 KiB
div.item > a > div.pic > ::before div.item > a > div.pic > ::before
www.pku.edu.cn/Public/static/themes/image/png92.png43.8 KiB37.9 KiB
艺术与文化 div.home7 > div.block > div.d2 > div#d1
www.pku.edu.cn/Uploads/Picture/2019/12/20/s5dfc40dc928fb.jpg47.2 KiB34.2 KiB
div.block > div.logo > a > img div.block > div.logo > a > img
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04147ee4a83.png28.3 KiB26.9 KiB
校园 · 生活 感受流光溢彩的青春 div.scroll > div.home7 > div.block > div.d1
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c77d7a66e70.jpg144.4 KiB24.1 KiB
div.part2 > div.logo > a > img div.part2 > div.logo > a > img
www.pku.edu.cn/Uploads/Picture/2019/12/05/s5de8762313bab.png17.7 KiB14.2 KiB
body > div.body_home > div.rr body > div.body_home > div.rr
www.pku.edu.cn/Public/static/themes/image/png27.png9.2 KiB6.9 KiB

Each subpart has specific improvement strategies. Ideally, most of the LCP time should be spent on loading the resources, not within delays.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:label label:Subpart valueType:text] map[key:duration label:Duration valueType:ms]]
items: [map[duration:1099.214 label:Time to first byte subpart:timeToFirstByte] map[duration:5912.416 label:Element render delay subpart:elementRenderDelay]]
lhId: page-19-DIV
nodeLabel: 北大医学厚道学堂正式成立，首发项目“未来医学教育领航者培养计划”同步启航
path: 2,HTML,1,BODY,8,DIV,1,DIV,0,DIV,0,DIV,1,DIV,0,DIV,1,DIV,3,DIV,0,A,0,DIV,0,DIV
selector: div.item > a > div.text > div.h
snippet: <div class="h">

HTTP/2 and HTTP/3 offer many benefits over HTTP/1.1, such as multiplexing. Learn more about using modern HTTP.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLProtocol
www.pku.edu.cn/http/1.1
www.pku.edu.cn/Public/static/themes/css/jquery.mCustomScrollbar.csshttp/1.1
www.pku.edu.cn/Public/static/themes/css/global.csshttp/1.1
www.pku.edu.cn/Public/static/themes/css/fix.csshttp/1.1
www.pku.edu.cn/Public/static/themes/js/jquery.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/jquery.easing.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/jquery.mousewheel.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/global.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/fun.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/plus/old/winscreen.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mChange.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mScroll.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/plus/vivus.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/jquery.mCustomScrollbar.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/iscroll.jshttp/1.1
www.pku.edu.cn/Public/static/themes/css/slick.csshttp/1.1
www.pku.edu.cn/Public/static/themes/js/slick.jshttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04147ee4a83.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2024/11/06/s672b1d5a8248e.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6ab0f45e.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2022/11/02/s6362348db2897.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c789787fad6.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6392fd51.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2022/11/22/s637cb8c134d80.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/22/s68d10dcacb977.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/08/s5decd8b95f388.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04176fbbfa3.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/image/pic65.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/27/s5e05ab4267239.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/31/s5e0aa9359ae68.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/05/s5de8762313bab.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/js/homeJson.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/plus/jquery.imgpreload.jshttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/04/17/s69e1c2a2f1019.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/04/09/s69d759af9ca1b.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/04/02/s69cdfe602790e.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d26ba8a5.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d1418721.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/02/27/s69a0fec9dcf3b.jpghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png27.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png23.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58ada3ef15.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58b3611072.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58b7aaab99.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58bbebf671.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c77d7a66e70.jpghttp/1.1
www.pku.edu.cn/Public/static/themes/image/more1b.svghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/20/s5dfc40dc928fb.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/17/s68ca4cd3c10bb.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/18/s5dfa062371400.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/18/s5dfa063869f70.jpghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png32.svghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png25.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png26.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/css/fonts/iconfont.woffhttp/1.1
www.pku.edu.cn/Public/static/themes/image/png5.pnghttp/1.1
www.pku.edu.cn/dat/recentList.xmlhttp/1.1
www.pku.edu.cn/dat/recentStatement.xmlhttp/1.1
www.pku.edu.cn/dat/topNews.jsonhttp/1.1
www.pku.edu.cn/dat/imgNews.jsonhttp/1.1
www.pku.edu.cn/dat/teachResearchNews.jsonhttp/1.1
www.pku.edu.cn/dat/mediaPKU.jsonhttp/1.1
www.pku.edu.cn/dat/forumPKU.jsonhttp/1.1
www.pku.edu.cn/dat/pkuPeople.jsonhttp/1.1
www.pku.edu.cn/dat/hotTopics.jsonhttp/1.1
www.pku.edu.cn/dat/img/7fc4f699f7bc45f39f49c2d2d292bc1c.jpghttp/1.1
www.pku.edu.cn/dat/img/fe7afc17eccc47c499adca9b6c549b4e.jpghttp/1.1
www.pku.edu.cn/dat/img/85d41f2c3212461b885294a7d7d996b3.jpeghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png92.pnghttp/1.1
www.pku.edu.cn/dat/img/4bdf82f5e8a24fcc9b4e108f570f317a.jpeghttp/1.1
www.pku.edu.cn/dat/img/15e75d5f2c624be9a8cf1374c317fcf4.jpeghttp/1.1
www.pku.edu.cn/dat/img/344b546ab3de42e885101859f6b8ed3b.jpghttp/1.1
www.pku.edu.cn/dat/img/b2080858ec064a049de34c1ca7eb81e9.pnghttp/1.1
www.pku.edu.cn/dat/img/6c7b130555df477791adf7fa0d08e4bf.jpghttp/1.1
www.pku.edu.cn/dat/img/3f24a9b3793f4520ae77c2d405badf92.jpghttp/1.1

Avoid chaining critical requests by reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load.

Why this matters

Performance issues directly impact user engagement and conversion rates.

description: [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints help the browser establish a connection earlier in the page load, saving time when the first request for that origin is made. The following are the origins that the page preconnected to.
title: Preconnected origins
value: no origins were preconnected
description: Add [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints to your most important origins, but try to use no more than 4.
title: Preconnect candidates
value: No additional origins are good candidates for preconnecting

Requests are blocking the page's initial render, which may delay LCP. Deferring or inlining can move these network requests out of the critical path.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLTransfer SizeDuration
www.pku.edu.cn/Public/static/themes/js/plus/old/winscreen.js1.7 KiB199 ms
www.pku.edu.cn/Public/static/themes/js/slick.js15.7 KiB499 ms
www.pku.edu.cn/Public/static/themes/js/jquery.mCustomScrollbar.js22.2 KiB799 ms
www.pku.edu.cn/Public/static/themes/js/iscroll.js12.8 KiB499 ms
www.pku.edu.cn/Public/static/themes/js/plus/vivus.js8.7 KiB499 ms
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mScroll.js4.8 KiB349 ms
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mChange.js1.8 KiB199 ms
www.pku.edu.cn/Public/static/themes/js/jquery.js33.1 KiB1.4 s
www.pku.edu.cn/Public/static/themes/css/global.css22.8 KiB1.1 s
www.pku.edu.cn/Public/static/themes/js/fun.js5.9 KiB349 ms
www.pku.edu.cn/Public/static/themes/js/global.js2.8 KiB199 ms
www.pku.edu.cn/Public/static/themes/js/jquery.mousewheel.js1.1 KiB199 ms
www.pku.edu.cn/Public/static/themes/js/jquery.easing.js1.2 KiB499 ms
www.pku.edu.cn/Public/static/themes/css/slick.css848 B499 ms
www.pku.edu.cn/Public/static/themes/css/fix.css11.0 KiB649 ms
www.pku.edu.cn/Public/static/themes/css/jquery.mCustomScrollbar.css2.7 KiB199 ms

These insights are also available in the Chrome DevTools Performance Panel - record a trace to view more detailed information.

Time to Interactive is the amount of time it takes for the page to become fully interactive. Learn more about the Time to Interactive metric.

Why this matters

Performance issues directly impact user engagement and conversion rates.

TTI

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

Why this matters

Performance issues directly impact user engagement and conversion rates.

ElementLayout shift score
北京大学第五届海军文化节举行 马来西亚拉曼大学校长访问北京大学 韩国友好人士代表团访问北京大学 中俄数学挑战基金研讨会在北京大学举行 2026北京大学管理质效年 div.home5 > div.block > div.content > div.list
0.153

Diagnostics

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

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 50 ms 2.1 KiB
URLTransfer SizeEst Savings
www.pku.edu.cn/Public/static/themes/css/global.css22.8 KiB2.1 KiB

Minifying JavaScript files can reduce payload sizes and script parse time. Learn how to minify JavaScript.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 150 ms 24.1 KiB
URLTransfer SizeEst Savings
www.pku.edu.cn/Public/static/themes/js/jquery.mCustomScrollbar.js21.8 KiB8.5 KiB
www.pku.edu.cn/Public/static/themes/js/slick.js15.3 KiB6.1 KiB
www.pku.edu.cn/Public/static/themes/js/plus/vivus.js8.4 KiB4.3 KiB
www.pku.edu.cn/Public/static/themes/js/iscroll.js12.4 KiB3.1 KiB
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mScroll.js4.5 KiB2.0 KiB

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.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 100 ms 17.4 KiB
URLTransfer SizeEst Savings
www.pku.edu.cn/Public/static/themes/css/global.css22.5 KiB17.4 KiB

Consider reducing the time spent parsing, compiling and executing JS. You may find delivering smaller JS payloads helps with this. Learn how to minimize main-thread work

Why this matters

Performance issues directly impact user engagement and conversion rates.

CategoryTime Spent
Other4.2 s
Rendering1.7 s
Style & Layout1.7 s
Script Evaluation839 ms
Parse HTML & CSS60 ms
Garbage Collection48 ms
Script Parsing & Compilation46 ms

Large network payloads cost users real money and are highly correlated with long load times. Learn how to reduce payload sizes.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLTransfer Size
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d1418721.jpg4.1 MiB
www.pku.edu.cn/dat/img/fe7afc17eccc47c499adca9b6c549b4e.jpg2.1 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/02/s69cdfe602790e.jpg2.1 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/17/s69e1c2a2f1019.jpg2.0 MiB
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d26ba8a5.jpg2.0 MiB
www.pku.edu.cn/dat/img/b2080858ec064a049de34c1ca7eb81e9.png1.9 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/09/s69d759af9ca1b.jpg1.4 MiB
www.pku.edu.cn/Uploads/Picture/2026/02/27/s69a0fec9dcf3b.jpg1.3 MiB
www.pku.edu.cn/dat/img/344b546ab3de42e885101859f6b8ed3b.jpg1.2 MiB
www.pku.edu.cn/dat/img/7fc4f699f7bc45f39f49c2d2d292bc1c.jpg1.1 MiB

Set an explicit width and height on image elements to reduce layout shifts and improve CLS. Learn how to set image dimensions

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL
div.pic > div.img > a > img div.pic > div.img > a > img
www.pku.edu.cn/dat/img/15e75d5f2c624be9a8cf1374c317fcf4.jpeg
div.share-box > a.share-item > span.code > img div.share-box > a.share-item > span.code > img
www.pku.edu.cn/Uploads/Picture/2019/12/31/s5e0aa9359ae68.png
div.pic > div.img > a > img div.pic > div.img > a > img
www.pku.edu.cn/dat/img/4bdf82f5e8a24fcc9b4e108f570f317a.jpeg
div.inner > div.l > a > img div.inner > div.l > a > img
www.pku.edu.cn/dat/img/85d41f2c3212461b885294a7d7d996b3.jpeg
div.block > div.logo > a > img div.block > div.logo > a > img
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04147ee4a83.png
div.share-box > a.share-item > span.code > img div.share-box > a.share-item > span.code > img
www.pku.edu.cn/Uploads/Picture/2019/12/27/s5e05ab4267239.jpg
div.part2 > div.logo > a > img div.part2 > div.logo > a > img
www.pku.edu.cn/Uploads/Picture/2019/12/05/s5de8762313bab.png
div.nav_mobile > div.logo > a > img div.nav_mobile > div.logo > a > img
www.pku.edu.cn/Uploads/Picture/2019/12/08/s5decd8b95f388.png
div > div.child > a > img._lazyload div > div.child > a > img._lazyload
div > div.child > a > img._lazyload div > div.child > a > img._lazyload
div > div.child > a > img._lazyload div > div.child > a > img._lazyload
div > div.child > a > img._lazyload div > div.child > a > img._lazyload
div > div.child > a > img._lazyload div > div.child > a > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div#slick-slide20 > div > div.child > img._lazyload div#slick-slide20 > div > div.child > img._lazyload
div#slick-slide21 > div > div.child > img._lazyload div#slick-slide21 > div > div.child > img._lazyload
div#slick-slide22 > div > div.child > img._lazyload div#slick-slide22 > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div#slick-slide30 > div > div.child > img._lazyload div#slick-slide30 > div > div.child > img._lazyload
div#slick-slide31 > div > div.child > img._lazyload div#slick-slide31 > div > div.child > img._lazyload
div#slick-slide32 > div > div.child > img._lazyload div#slick-slide32 > div > div.child > img._lazyload
div#slick-slide33 > div > div.child > img._lazyload div#slick-slide33 > div > div.child > img._lazyload
div#slick-slide34 > div > div.child > img._lazyload div#slick-slide34 > div > div.child > img._lazyload
div#slick-slide35 > div > div.child > img._lazyload div#slick-slide35 > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.part1 > div.list > div.item > img._lazyload div.part1 > div.list > div.item > img._lazyload
div.part1 > div.list > div.item > img._lazyload div.part1 > div.list > div.item > img._lazyload
div.part1 > div.list > div.item > img._lazyload div.part1 > div.list > div.item > img._lazyload
div.part1 > div.list > div.item > img._lazyload div.part1 > div.list > div.item > img._lazyload

More information about the performance of your application. These numbers don't directly affect the Performance score.

●Max Potential First Input Delay 120 ms
●Document request latency
●Optimize DOM size
●Forced reflow
●Optimize viewport for mobile
●Reduce unused JavaScript
●JavaScript execution time 0.8 s
●Avoid long main-thread tasks 4 long tasks found
●Page didn't prevent back/forward cache restoration
●Network Requests
●Network Round Trip Times 320 ms
●Server Backend Latencies 50 ms
●Tasks
●Diagnostics
●Metrics
●Screenshot Thumbnails
●Final Screenshot
●Script Treemap Data
●Resources Summary
●Avoid multiple page redirects
●Initial server response time was short Root document took 550 ms
○INP breakdown
○LCP request discovery
○User Timing marks and measures
○Avoid non-composited animations
69

Accessibility

These checks highlight opportunities to improve the accessibility of your web app. Automatic detection can only detect a subset of issues and does not guarantee the accessibility of your web app, so manual testing is also encouraged.

Internationalization and localization

If a page doesn't specify a `lang` attribute, a screen reader assumes that the page is in the default language that the user chose when setting up the screen reader. If the page isn't actually in the default language, then the screen reader might not announce the page's text correctly. Learn more about the `lang` attribute.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
html.home html.home

These are opportunities to improve the interpretation of your content by users in different locales.

Names and labels

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.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
div.inner > div.l > a > img div.inner > div.l > a > img

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.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
div.d2 > div.block > div.logo > a div.d2 > div.block > div.logo > a
div#slick-slide00 > div > div.child > a.a1 div#slick-slide00 > div > div.child > a.a1
div#slick-slide00 > div > div.child > a.a2 div#slick-slide00 > div > div.child > a.a2
div.inner > div.pic > div.img > a div.inner > div.pic > div.img > a
div.inner > div.pic > div.img > a div.inner > div.pic > div.img > a
div.block > div.list > div.item > a div.block > div.list > div.item > a
div.block > div.list > div.item > a div.block > div.list > div.item > a
div.block > div.list > div.item > a div.block > div.list > div.item > a
div.block > div.list > div.item > a div.block > div.list > div.item > a
div.text > div.inner > div.l > a div.text > div.inner > div.l > a
div.inner > div.pic > div.img > a div.inner > div.pic > div.img > a
div.inner > div.pic > div.img > a div.inner > div.pic > div.img > a
div.block > div.d2 > div#d1 > a div.block > div.d2 > div#d1 > a
div.block > div.d2 > div#d2 > a div.block > div.d2 > div#d2 > a
div.block > div.d2 > div#d3 > a div.block > div.d2 > div#d3 > a
div.block > div.d4 > div#d4 > a div.block > div.d4 > div#d4 > a
div.block > div.d4 > div#d5 > a div.block > div.d4 > div#d5 > a
div.block > div.d4 > div#d6 > a div.block > div.d4 > div#d6 > a
div.part1 > div.list > div.item > a div.part1 > div.list > div.item > a
div.part1 > div.list > div.item > a div.part1 > div.list > div.item > a
div.part1 > div.list > div.item > a div.part1 > div.list > div.item > a
div.part1 > div.list > div.item > a div.part1 > div.list > div.item > a
div.footer > div.part2 > div.logo > a div.footer > div.part2 > div.logo > a

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.

Best practices

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.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
head > meta head > meta

Touch targets with sufficient size and spacing help users who may have difficulty targeting small controls to activate the targets. Learn more about touch targets.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
新闻 div.part1 > div.nav_foot > div.inner > a
招生 div.part1 > div.nav_foot > div.inner > a
招聘 div.part1 > div.nav_foot > div.inner > a
捐赠 div.part1 > div.nav_foot > div.inner > a
校园地图 div.part1 > div.nav_foot > div.inner > a
校历 div.part1 > div.nav_foot > div.inner > a
燕园特写 div.part1 > div.nav_foot > div.inner > a
未名BBS div.part1 > div.nav_foot > div.inner > a

These items highlight common accessibility best practices.

Navigation

A value greater than 0 implies an explicit navigation ordering. Although technically valid, this often creates frustrating experiences for users who rely on assistive technologies. Learn more about the `tabindex` attribute.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
北大 · 要闻 北京大学扎实开展树立和践行正确政绩观学习教育 越南青年“红色研学之旅”之“不忘初心”研学营走进北京大学 世界气象组织秘书长席列斯特·绍罗访问北… body > div.body_b

These are opportunities to improve keyboard navigation in your application.

○Interactive controls are keyboard focusable
○Interactive elements indicate their purpose and state
○The page has a logical tab order
○Visual order on the page follows DOM order
○User focus is not accidentally trapped in a region
○The user's focus is directed to new content added to the page
○HTML5 landmark elements are used to improve navigation
○Offscreen content is hidden from assistive technology
○Custom controls have associated labels
○Custom controls have ARIA roles
●`[aria-*]` attributes match their roles
●`[aria-hidden="true"]` is not present on the document `<body>`
●`[role]`s have all required `[aria-*]` attributes
●`[role]` values are valid
●`[aria-*]` attributes have valid values
●`[aria-*]` attributes are valid and not misspelled
●ARIA attributes are used as specified for the element's role
●`[aria-hidden="true"]` elements do not contain focusable descendents
●Elements use only permitted ARIA attributes
●Background and foreground colors have a sufficient contrast ratio
●Document has a `<title>` element
●Links are distinguishable without relying on color.
●Document has a main landmark.
●Deprecated ARIA roles were not used
●The page contains a heading, skip link, or landmark region
●Identical links have the same purpose.
○`[accesskey]` values are unique
○`button`, `link`, and `menuitem` elements have accessible names
○Elements with `role="dialog"` or `role="alertdialog"` have accessible names.
○ARIA input fields have accessible names
○ARIA `meter` elements have accessible names
○ARIA `progressbar` elements have accessible names
○Elements with an ARIA `[role]` that require children to contain a specific `[role]` have all required children.
○`[role]`s are contained by their required parent element
○Elements with the `role=text` attribute do not have focusable descendents.
○ARIA toggle fields have accessible names
○ARIA `tooltip` elements have accessible names
○ARIA `treeitem` elements have accessible names
○Buttons have an accessible name
○`<dl>`'s contain only properly-ordered `<dt>` and `<dd>` groups, `<script>`, `<template>` or `<div>` elements.
○Definition list items are wrapped in `<dl>` elements
○ARIA IDs are unique
○No form fields have multiple labels
○`<frame>` or `<iframe>` elements have a title
○Heading elements appear in a sequentially-descending order
○`<html>` element has a valid value for its `[lang]` attribute
○`<html>` element has an `[xml:lang]` attribute with the same base language as the `[lang]` attribute.
○Input buttons have discernible text.
○`<input type="image">` elements have `[alt]` text
○Form elements have associated labels
○Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`).
○List items (`<li>`) are contained within `<ul>`, `<ol>` or `<menu>` parent elements
○The document does not use `<meta http-equiv="refresh">`
○`<object>` elements have alternate text
○Select elements have associated label elements.
○Skip links are focusable.
○Cells in a `<table>` element that use the `[headers]` attribute refer to table cells within the same table.
○`<th>` elements and elements with `[role="columnheader"/"rowheader"]` have data cells they describe.
○`[lang]` attributes have a valid value
○`<video>` elements contain a `<track>` element with `[kind="captions"]`
○Tables have different content in the summary attribute and `<caption>`.
○All heading elements contain content.
○Uses ARIA roles only on compatible elements
○Image elements do not have `[alt]` attributes that are redundant text.
○Elements with visible text labels have matching accessible names.
○Tables use `<caption>` instead of cells with the `[colspan]` attribute to indicate a caption.
○`<td>` elements in a large `<table>` have one or more table headers.
100

Best Practices

●Uses HTTPS
●Avoids deprecated APIs
●Avoids third-party cookies
●Allows users to paste into input fields
●Avoids requesting the geolocation permission on page load
●Avoids requesting the notification permission on page load
●Displays images with correct aspect ratio
●Serves images with appropriate resolution
●Page has the HTML doctype
●Properly defines charset
●No browser errors logged to the console
●No issues in the `Issues` panel in Chrome Devtools
●Ensure CSP is effective against XSS attacks
●Use a strong HSTS policy
●Ensure proper origin isolation with COOP
●Mitigate clickjacking with XFO or CSP
●Mitigate DOM-based XSS with Trusted Types
●Detected JavaScript libraries
●Page has valid source maps
○Redirects HTTP traffic to HTTPS
82

SEO

These checks ensure that your page is following basic search engine optimization advice. There are many additional factors Lighthouse does not score here that may affect your search ranking, including performance on Core Web Vitals. Learn more about Google Search Essentials.

Crawling and Indexing

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 how to make links crawlable

Why this matters

Performance issues directly impact user engagement and conversion rates.

Uncrawlable Link
div.slick-slide > div > div.child > a.a1 div.slick-slide > div > div.child > a.a1
div#slick-slide01 > div > div.child > a.a1 div#slick-slide01 > div > div.child > a.a1
div#slick-slide05 > div > div.child > a.a1 div#slick-slide05 > div > div.child > a.a1
div.slick-slide > div > div.child > a.a1 div.slick-slide > div > div.child > a.a1
div.slick-slide > div > div.child > a.a1 div.slick-slide > div > div.child > a.a1
div.slick-slide > div > div.child > a div.slick-slide > div > div.child > a
div.slick-slide > div > div.child > a div.slick-slide > div > div.child > a
通知公告 div.l > div.title > div.fz40 > a.now
北大声明 div.l > div.title > div.fz40 > a
div#slick-slide30 > div > div.child > a div#slick-slide30 > div > div.child > a
div.slick-slide > div > div.child > a div.slick-slide > div > div.child > a

To appear in search results, crawlers need access to your app.

Content Best Practices

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.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
div.inner > div.l > a > img div.inner > div.l > a > img

Format your HTML in a way that enables crawlers to better understand your app’s content.

○Structured data is valid
●Page isn’t blocked from indexing
●Document has a `<title>` element
●Document has a meta description
●Page has successful HTTP status code
●Links have descriptive text
●Document has a valid `hreflang`
○robots.txt is valid
○Document has a valid `rel=canonical`

Lighthouse Scores

Industry-standard audits powered by Google Lighthouse. — Desktop

90
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
68
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
96
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
82
SEO Measures basic SEO optimizations: meta tags, crawlability, link text, and mobile friendliness.

Core Web Vitals

Key metrics that affect user experience. — Desktop

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

548 ms

Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.

548 ms

Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.

0 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.000

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

5.29 s

Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.

548 ms

Detailed Report

Audit breakdown by category with detailed findings.

90

Performance

Insights

Remove large, duplicate JavaScript modules from bundles to reduce unnecessary bytes consumed by network activity.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Polyfills and transforms enable older browsers to use new JavaScript features. However, many aren't necessary for modern browsers. Consider modifying your JavaScript build process to not transpile Baseline features, unless you know you must support older browsers. Learn why most sites can deploy ES6+ code without transpiling

Why this matters

Shipping ES5 transpiled code to modern browsers wastes bytes — every user with an evergreen browser pays for compatibility you don't need.

Learn more ▾

Most users today run browsers that natively support ES6+, async/await, optional chaining, and the rest of modern JavaScript. Transpiling to ES5 'just in case' adds 20-40% to your bundle for no benefit. Configure your build to target a modern browserslist, or ship a differential bundle pair (modern + legacy) with the module/nomodule pattern.

Source: Google web.dev / Lighthouse

3rd party code can significantly impact load performance. Reduce and defer loading of 3rd party code to prioritize your page's content.

Why this matters

Performance issues directly impact user engagement and conversion rates.

A long cache lifetime can speed up repeat visits to your page. Learn more about caching.

Why this matters

Performance issues directly impact user engagement and conversion rates.

RequestCache TTLTransfer Size
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d1418721.jpg0.0 ms4.1 MiB
www.pku.edu.cn/dat/img/fe7afc17eccc47c499adca9b6c549b4e.jpg0.0 ms2.1 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/02/s69cdfe602790e.jpg0.0 ms2.1 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/17/s69e1c2a2f1019.jpg0.0 ms2.0 MiB
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www.pku.edu.cn/dat/img/b2080858ec064a049de34c1ca7eb81e9.png0.0 ms1.9 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/09/s69d759af9ca1b.jpg0.0 ms1.4 MiB
www.pku.edu.cn/Uploads/Picture/2026/02/27/s69a0fec9dcf3b.jpg0.0 ms1.3 MiB
www.pku.edu.cn/dat/img/344b546ab3de42e885101859f6b8ed3b.jpg0.0 ms1.2 MiB
www.pku.edu.cn/Uploads/Picture/2025/09/17/s68ca4cd3c10bb.png0.0 ms697.4 KiB
www.pku.edu.cn/Uploads/Picture/2025/09/22/s68d10dcacb977.jpg0.0 ms567.5 KiB
www.pku.edu.cn/Uploads/Picture/2022/11/02/s6362348db2897.png0.0 ms543.5 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/31/s5e0aa9359ae68.png0.0 ms528.9 KiB
www.pku.edu.cn/Uploads/Picture/2022/11/22/s637cb8c134d80.jpg0.0 ms312.4 KiB
www.pku.edu.cn/Uploads/Picture/2024/11/06/s672b1d5a8248e.jpg0.0 ms232.3 KiB
www.pku.edu.cn/dat/img/3f24a9b3793f4520ae77c2d405badf92.jpg0.0 ms209.0 KiB
www.pku.edu.cn/dat/img/6c7b130555df477791adf7fa0d08e4bf.jpg0.0 ms178.0 KiB
www.pku.edu.cn/dat/img/85d41f2c3212461b885294a7d7d996b3.jpeg0.0 ms166.9 KiB
www.pku.edu.cn/dat/img/15e75d5f2c624be9a8cf1374c317fcf4.jpeg0.0 ms158.7 KiB
www.pku.edu.cn/dat/img/4bdf82f5e8a24fcc9b4e108f570f317a.jpeg0.0 ms155.7 KiB
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c77d7a66e70.jpg0.0 ms144.7 KiB
www.pku.edu.cn/Public/static/themes/image/pic65.jpg0.0 ms132.5 KiB
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c789787fad6.jpg0.0 ms125.3 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04176fbbfa3.png0.0 ms50.5 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/20/s5dfc40dc928fb.jpg0.0 ms47.4 KiB
www.pku.edu.cn/Public/static/themes/image/png92.png0.0 ms44.0 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/27/s5e05ab4267239.jpg0.0 ms41.4 KiB
www.pku.edu.cn/Public/static/themes/css/fonts/iconfont.woff0.0 ms39.9 KiB
www.pku.edu.cn/Public/static/themes/image/png96.png0.0 ms35.1 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.js0.0 ms33.1 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04147ee4a83.png0.0 ms28.6 KiB
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6ab0f45e.jpg0.0 ms27.2 KiB
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6392fd51.jpg0.0 ms23.8 KiB
www.pku.edu.cn/Public/static/themes/image/bg8.png0.0 ms23.8 KiB
www.pku.edu.cn/Public/static/themes/css/global.css0.0 ms22.8 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.mCustomScrollbar.js0.0 ms22.2 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/05/s5de8762313bab.png0.0 ms18.0 KiB
www.pku.edu.cn/Public/static/themes/image/bg9a.svg0.0 ms16.9 KiB
www.pku.edu.cn/Public/static/themes/js/slick.js0.0 ms15.7 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58ada3ef15.jpg0.0 ms14.7 KiB
www.pku.edu.cn/Public/static/themes/js/iscroll.js0.0 ms12.8 KiB
www.pku.edu.cn/Public/static/themes/css/fix.css0.0 ms11.0 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58b3611072.jpg0.0 ms10.3 KiB
www.pku.edu.cn/Public/static/themes/image/png27.png0.0 ms9.5 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58bbebf671.jpg0.0 ms9.0 KiB
www.pku.edu.cn/Public/static/themes/js/plus/vivus.js0.0 ms8.7 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/18/s5dfa063869f70.jpg0.0 ms7.8 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58b7aaab99.jpg0.0 ms7.1 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/08/s5decd8b95f388.png0.0 ms6.7 KiB
www.pku.edu.cn/Public/static/themes/js/fun.js0.0 ms5.9 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/18/s5dfa062371400.jpg0.0 ms5.0 KiB
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mScroll.js0.0 ms4.8 KiB
www.pku.edu.cn/Public/static/themes/image/png25.png0.0 ms4.4 KiB
/collector/statistic.js?channelId=&channelName=&articleId...0.0 ms3.5 KiB
www.pku.edu.cn/Public/static/themes/image/png26.png0.0 ms2.9 KiB
www.pku.edu.cn/Public/static/themes/js/global.js0.0 ms2.8 KiB
www.pku.edu.cn/Public/static/themes/css/jquery.mCustomScrollbar.css0.0 ms2.7 KiB
www.pku.edu.cn/Public/static/themes/image/png23.png0.0 ms2.4 KiB
www.pku.edu.cn/Public/static/themes/js/homeJson.js0.0 ms2.2 KiB
www.pku.edu.cn/Public/static/themes/js/plus/jquery.imgpreload.js0.0 ms2.0 KiB
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mChange.js0.0 ms1.8 KiB
www.pku.edu.cn/Public/static/themes/js/plus/old/winscreen.js0.0 ms1.7 KiB
www.pku.edu.cn/Public/static/themes/image/png34.png0.0 ms1.6 KiB
www.pku.edu.cn/Public/static/themes/image/png32.svg0.0 ms1.3 KiB
www.pku.edu.cn/Public/static/themes/image/more1a.svg0.0 ms1.3 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.easing.js0.0 ms1.2 KiB
www.pku.edu.cn/Public/static/themes/image/more1b.svg0.0 ms1.2 KiB
www.pku.edu.cn/Public/static/themes/image/more1.svg0.0 ms1.2 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.mousewheel.js0.0 ms1.1 KiB
www.pku.edu.cn/Public/static/themes/css/slick.css0.0 ms848 B
www.pku.edu.cn/dat/img/7fc4f699f7bc45f39f49c2d2d292bc1c.jpg0.0 ms0 B

Consider setting font-display to swap or optional to ensure text is consistently visible. swap can be further optimized to mitigate layout shifts with font metric overrides.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLEst Savings
www.pku.edu.cn/Public/static/themes/css/fonts/iconfont.woff270 ms

Each subpart has specific improvement strategies. Ideally, most of the LCP time should be spent on loading the resources, not within delays.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:label label:Subpart valueType:text] map[key:duration label:Duration valueType:ms]]
items: [map[duration:1100.524 label:Time to first byte subpart:timeToFirstByte] map[duration:1475.502 label:Element render delay subpart:elementRenderDelay]]
lhId: page-0-DIV
nodeLabel: 北京大学校园开放日暨本科招生宣讲会
path: 2,HTML,1,BODY,7,DIV,2,DIV,0,DIV,0,DIV,0,DIV,1,DIV,0,DIV,0,DIV,1,DIV
selector: div#slick-slide00 > div > div.child > div.fz30
snippet: <div class="fz30">

HTTP/2 and HTTP/3 offer many benefits over HTTP/1.1, such as multiplexing. Learn more about using modern HTTP.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLProtocol
www.pku.edu.cn/http/1.1
www.pku.edu.cn/Public/static/themes/css/jquery.mCustomScrollbar.csshttp/1.1
www.pku.edu.cn/Public/static/themes/css/global.csshttp/1.1
www.pku.edu.cn/Public/static/themes/css/fix.csshttp/1.1
www.pku.edu.cn/Public/static/themes/js/jquery.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/jquery.easing.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/jquery.mousewheel.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/global.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/fun.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/plus/old/winscreen.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mChange.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mScroll.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/plus/vivus.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/jquery.mCustomScrollbar.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/iscroll.jshttp/1.1
www.pku.edu.cn/Public/static/themes/css/slick.csshttp/1.1
www.pku.edu.cn/Public/static/themes/js/slick.jshttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04147ee4a83.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2024/11/06/s672b1d5a8248e.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6ab0f45e.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2022/11/02/s6362348db2897.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c789787fad6.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6392fd51.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2022/11/22/s637cb8c134d80.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/22/s68d10dcacb977.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/08/s5decd8b95f388.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04176fbbfa3.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/image/pic65.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/27/s5e05ab4267239.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/31/s5e0aa9359ae68.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/05/s5de8762313bab.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/js/homeJson.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/plus/jquery.imgpreload.jshttp/1.1
www.pku.edu.cn/Public/static/themes/image/png96.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/04/17/s69e1c2a2f1019.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/04/09/s69d759af9ca1b.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/04/02/s69cdfe602790e.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d26ba8a5.jpghttp/1.1
www.pku.edu.cn/Public/static/themes/css/fonts/iconfont.woffhttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d1418721.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/02/27/s69a0fec9dcf3b.jpghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png27.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png23.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/image/more1a.svghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58ada3ef15.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58b3611072.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58b7aaab99.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58bbebf671.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c77d7a66e70.jpghttp/1.1
www.pku.edu.cn/Public/static/themes/image/more1b.svghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/20/s5dfc40dc928fb.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/17/s68ca4cd3c10bb.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/18/s5dfa062371400.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/18/s5dfa063869f70.jpghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png32.svghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png25.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png26.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png34.pnghttp/1.1
www.pku.edu.cn/dat/recentList.xmlhttp/1.1
www.pku.edu.cn/dat/recentStatement.xmlhttp/1.1
www.pku.edu.cn/dat/topNews.jsonhttp/1.1
www.pku.edu.cn/dat/imgNews.jsonhttp/1.1
www.pku.edu.cn/dat/teachResearchNews.jsonhttp/1.1
www.pku.edu.cn/dat/mediaPKU.jsonhttp/1.1
www.pku.edu.cn/dat/forumPKU.jsonhttp/1.1
www.pku.edu.cn/dat/pkuPeople.jsonhttp/1.1
www.pku.edu.cn/dat/hotTopics.jsonhttp/1.1
www.pku.edu.cn/Public/static/themes/image/bg9a.svghttp/1.1
www.pku.edu.cn/dat/img/7fc4f699f7bc45f39f49c2d2d292bc1c.jpghttp/1.1
www.pku.edu.cn/dat/img/fe7afc17eccc47c499adca9b6c549b4e.jpghttp/1.1
www.pku.edu.cn/dat/img/85d41f2c3212461b885294a7d7d996b3.jpeghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png92.pnghttp/1.1
www.pku.edu.cn/dat/img/4bdf82f5e8a24fcc9b4e108f570f317a.jpeghttp/1.1
www.pku.edu.cn/dat/img/15e75d5f2c624be9a8cf1374c317fcf4.jpeghttp/1.1
www.pku.edu.cn/dat/img/344b546ab3de42e885101859f6b8ed3b.jpghttp/1.1
www.pku.edu.cn/dat/img/b2080858ec064a049de34c1ca7eb81e9.pnghttp/1.1
www.pku.edu.cn/dat/img/6c7b130555df477791adf7fa0d08e4bf.jpghttp/1.1
www.pku.edu.cn/dat/img/3f24a9b3793f4520ae77c2d405badf92.jpghttp/1.1
www.pku.edu.cn/Public/static/themes/image/more1.svghttp/1.1
www.pku.edu.cn/Public/static/themes/image/bg14.svghttp/1.1
www.pku.edu.cn/Public/static/themes/image/bg5.svghttp/1.1
www.pku.edu.cn/Public/static/themes/image/bg8.pnghttp/1.1

Avoid chaining critical requests by reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load.

Why this matters

Performance issues directly impact user engagement and conversion rates.

description: [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints help the browser establish a connection earlier in the page load, saving time when the first request for that origin is made. The following are the origins that the page preconnected to.
title: Preconnected origins
value: no origins were preconnected
description: Add [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints to your most important origins, but try to use no more than 4.
title: Preconnect candidates
value: No additional origins are good candidates for preconnecting

Requests are blocking the page's initial render, which may delay LCP. Deferring or inlining can move these network requests out of the critical path.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLTransfer SizeDuration
www.pku.edu.cn/Public/static/themes/js/jquery.mCustomScrollbar.js22.2 KiB127 ms
www.pku.edu.cn/Public/static/themes/js/slick.js15.7 KiB87 ms
www.pku.edu.cn/Public/static/themes/js/iscroll.js12.8 KiB87 ms
www.pku.edu.cn/Public/static/themes/js/plus/vivus.js8.7 KiB87 ms
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mScroll.js4.8 KiB
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mChange.js1.8 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.js33.1 KiB287 ms
www.pku.edu.cn/Public/static/themes/js/plus/old/winscreen.js1.7 KiB
www.pku.edu.cn/Public/static/themes/js/fun.js5.9 KiB
www.pku.edu.cn/Public/static/themes/js/global.js2.8 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.mousewheel.js1.1 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.easing.js1.2 KiB127 ms
www.pku.edu.cn/Public/static/themes/css/global.css22.8 KiB207 ms
www.pku.edu.cn/Public/static/themes/css/slick.css848 B127 ms
www.pku.edu.cn/Public/static/themes/css/fix.css11.0 KiB127 ms
www.pku.edu.cn/Public/static/themes/css/jquery.mCustomScrollbar.css2.7 KiB

Reducing the download time of images can improve the perceived load time of the page and LCP. Learn more about optimizing image size

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLResource SizeEst Savings
我国科学家近日在光通信和6G领域取得突破性进展 div.slick-track > div.slick-slide > div > div.child
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d1418721.jpg4.1 MiB2.8 MiB
北京大学2025-2026学年“应乐而声”校园十佳歌手大赛总决赛举行 div.slick-track > div.slick-slide > div > div.child
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d26ba8a5.jpg2.0 MiB1.7 MiB
北京大学区域与国别研究院建院八周年 div.slick-track > div.slick-slide > div > div.child
www.pku.edu.cn/Uploads/Picture/2026/04/09/s69d759af9ca1b.jpg1.4 MiB1.1 MiB
全球首个靶向整合素的创新核药获批上市 北大为中国核医学70周年献礼 div.slick-track > div.slick-slide > div > div.child
www.pku.edu.cn/Uploads/Picture/2026/04/02/s69cdfe602790e.jpg2.1 MiB820.5 KiB
北京大学校园开放日暨本科招生宣讲会 div.slick-track > div.slick-slide > div > div.child
www.pku.edu.cn/Uploads/Picture/2026/04/17/s69e1c2a2f1019.jpg2.0 MiB747.5 KiB
div.block > div.logo > a > img div.block > div.logo > a > img
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04147ee4a83.png28.3 KiB26.8 KiB
body > div.body_home > div.rr body > div.body_home > div.rr
www.pku.edu.cn/Public/static/themes/image/png27.png9.2 KiB6.9 KiB

These insights are also available in the Chrome DevTools Performance Panel - record a trace to view more detailed information.

Diagnostics

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

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 0.0 ms 2.1 KiB
URLTransfer SizeEst Savings
www.pku.edu.cn/Public/static/themes/css/global.css22.8 KiB2.1 KiB

Minifying JavaScript files can reduce payload sizes and script parse time. Learn how to minify JavaScript.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 0.0 ms 24.1 KiB
URLTransfer SizeEst Savings
www.pku.edu.cn/Public/static/themes/js/jquery.mCustomScrollbar.js21.8 KiB8.5 KiB
www.pku.edu.cn/Public/static/themes/js/slick.js15.3 KiB6.1 KiB
www.pku.edu.cn/Public/static/themes/js/plus/vivus.js8.4 KiB4.3 KiB
www.pku.edu.cn/Public/static/themes/js/iscroll.js12.4 KiB3.1 KiB
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mScroll.js4.5 KiB2.0 KiB

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.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 0.0 ms 26.6 KiB
URLTransfer SizeEst Savings
www.pku.edu.cn/Public/static/themes/css/global.css22.5 KiB16.2 KiB
www.pku.edu.cn/Public/static/themes/css/fix.css10.7 KiB10.4 KiB

Large network payloads cost users real money and are highly correlated with long load times. Learn how to reduce payload sizes.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLTransfer Size
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d1418721.jpg4.1 MiB
www.pku.edu.cn/dat/img/fe7afc17eccc47c499adca9b6c549b4e.jpg2.1 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/02/s69cdfe602790e.jpg2.1 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/17/s69e1c2a2f1019.jpg2.0 MiB
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d26ba8a5.jpg2.0 MiB
www.pku.edu.cn/dat/img/b2080858ec064a049de34c1ca7eb81e9.png1.9 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/09/s69d759af9ca1b.jpg1.4 MiB
www.pku.edu.cn/Uploads/Picture/2026/02/27/s69a0fec9dcf3b.jpg1.3 MiB
www.pku.edu.cn/dat/img/344b546ab3de42e885101859f6b8ed3b.jpg1.2 MiB
www.pku.edu.cn/dat/img/7fc4f699f7bc45f39f49c2d2d292bc1c.jpg1.0 MiB

Consider reducing the time spent parsing, compiling and executing JS. You may find delivering smaller JS payloads helps with this. Learn how to minimize main-thread work

Why this matters

Performance issues directly impact user engagement and conversion rates.

CategoryTime Spent
Other1.5 s
Style & Layout643 ms
Rendering559 ms
Script Evaluation258 ms
Garbage Collection20 ms
Parse HTML & CSS18 ms
Script Parsing & Compilation14 ms

Set an explicit width and height on image elements to reduce layout shifts and improve CLS. Learn how to set image dimensions

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL
div.pic > div.img > a > img div.pic > div.img > a > img
www.pku.edu.cn/dat/img/15e75d5f2c624be9a8cf1374c317fcf4.jpeg
div.share-box > a.share-item > span.code > img div.share-box > a.share-item > span.code > img
www.pku.edu.cn/Uploads/Picture/2019/12/31/s5e0aa9359ae68.png
div.pic > div.img > a > img div.pic > div.img > a > img
www.pku.edu.cn/dat/img/4bdf82f5e8a24fcc9b4e108f570f317a.jpeg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/22/s68d10dcacb977.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/22/s68d10dcacb977.jpg
div.inner > div.l > a > img div.inner > div.l > a > img
www.pku.edu.cn/dat/img/85d41f2c3212461b885294a7d7d996b3.jpeg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6ab0f45e.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6392fd51.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6ab0f45e.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6392fd51.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2024/11/06/s672b1d5a8248e.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2024/11/06/s672b1d5a8248e.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2022/11/02/s6362348db2897.png
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2022/11/02/s6362348db2897.png
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c789787fad6.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c789787fad6.jpg
div.block > div.logo > a > img div.block > div.logo > a > img
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04147ee4a83.png
div.block > div.logo > a > img div.block > div.logo > a > img
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04176fbbfa3.png
div.inner > div.logo > a > img div.inner > div.logo > a > img
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04176fbbfa3.png
div.share-box > a.share-item > span.code > img div.share-box > a.share-item > span.code > img
www.pku.edu.cn/Uploads/Picture/2019/12/27/s5e05ab4267239.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2022/11/22/s637cb8c134d80.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2022/11/22/s637cb8c134d80.jpg
div.part2 > div.logo > a > img div.part2 > div.logo > a > img
www.pku.edu.cn/Uploads/Picture/2019/12/05/s5de8762313bab.png
div > div.child > a > img._lazyload div > div.child > a > img._lazyload
div > div.child > a > img._lazyload div > div.child > a > img._lazyload
div > div.child > a > img._lazyload div > div.child > a > img._lazyload
div > div.child > a > img._lazyload div > div.child > a > img._lazyload
div > div.child > a > img._lazyload div > div.child > a > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div#slick-slide20 > div > div.child > img._lazyload div#slick-slide20 > div > div.child > img._lazyload
div#slick-slide21 > div > div.child > img._lazyload div#slick-slide21 > div > div.child > img._lazyload
div#slick-slide22 > div > div.child > img._lazyload div#slick-slide22 > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div#slick-slide30 > div > div.child > img._lazyload div#slick-slide30 > div > div.child > img._lazyload
div#slick-slide31 > div > div.child > img._lazyload div#slick-slide31 > div > div.child > img._lazyload
div#slick-slide32 > div > div.child > img._lazyload div#slick-slide32 > div > div.child > img._lazyload
div#slick-slide33 > div > div.child > img._lazyload div#slick-slide33 > div > div.child > img._lazyload
div#slick-slide34 > div > div.child > img._lazyload div#slick-slide34 > div > div.child > img._lazyload
div#slick-slide35 > div > div.child > img._lazyload div#slick-slide35 > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.part1 > div.list > div.item > img._lazyload div.part1 > div.list > div.item > img._lazyload
div.part1 > div.list > div.item > img._lazyload div.part1 > div.list > div.item > img._lazyload
div.part1 > div.list > div.item > img._lazyload div.part1 > div.list > div.item > img._lazyload
div.part1 > div.list > div.item > img._lazyload div.part1 > div.list > div.item > img._lazyload

More information about the performance of your application. These numbers don't directly affect the Performance score.

●Layout shift culprits
●Document request latency
●Optimize DOM size
●Forced reflow
●Optimize viewport for mobile
●Time to Interactive 0.5 s
●Max Potential First Input Delay 30 ms
●Reduce unused JavaScript
●JavaScript execution time 0.3 s
●Avoid non-composited animations 6 animated elements found
●Page didn't prevent back/forward cache restoration
●Network Requests
●Network Round Trip Times 320 ms
●Server Backend Latencies 50 ms
●Tasks
●Diagnostics
●Metrics
●Screenshot Thumbnails
●Final Screenshot
●Script Treemap Data
●Resources Summary
●Avoid multiple page redirects
●Initial server response time was short Root document took 550 ms
●Avoid large layout shifts 15 layout shifts found
○INP breakdown
○LCP request discovery
○User Timing marks and measures
○Avoid long main-thread tasks
68

Accessibility

These checks highlight opportunities to improve the accessibility of your web app. Automatic detection can only detect a subset of issues and does not guarantee the accessibility of your web app, so manual testing is also encouraged.

ARIA

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

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
123456 div.body_home > div.banner > div.navg > ul.slick-dots

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.

Internationalization and localization

If a page doesn't specify a `lang` attribute, a screen reader assumes that the page is in the default language that the user chose when setting up the screen reader. If the page isn't actually in the default language, then the screen reader might not announce the page's text correctly. Learn more about the `lang` attribute.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
html.home html.home

These are opportunities to improve the interpretation of your content by users in different locales.

Names and labels

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.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
div.inner > div.l > a > img div.inner > div.l > a > img

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.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
div.d2 > div.block > div.logo > a div.d2 > div.block > div.logo > a
div#slick-slide00 > div > div.child > a.a1 div#slick-slide00 > div > div.child > a.a1
div#slick-slide00 > div > div.child > a.a2 div#slick-slide00 > div > div.child > a.a2
div.d2 > div.block > div.logo > a div.d2 > div.block > div.logo > a
div.inner > div.pic > div.img > a div.inner > div.pic > div.img > a
div.inner > div.pic > div.img > a div.inner > div.pic > div.img > a
div.block > div.list > div.item > a div.block > div.list > div.item > a
div.block > div.list > div.item > a div.block > div.list > div.item > a
div.block > div.list > div.item > a div.block > div.list > div.item > a
div.block > div.list > div.item > a div.block > div.list > div.item > a
div.text > div.inner > div.l > a div.text > div.inner > div.l > a
div.inner > div.pic > div.img > a div.inner > div.pic > div.img > a
div.inner > div.pic > div.img > a div.inner > div.pic > div.img > a
div.block > div.d2 > div#d1 > a div.block > div.d2 > div#d1 > a
div.block > div.d2 > div#d2 > a div.block > div.d2 > div#d2 > a
div.block > div.d2 > div#d3 > a div.block > div.d2 > div#d3 > a
div.block > div.d4 > div#d4 > a div.block > div.d4 > div#d4 > a
div.block > div.d4 > div#d5 > a div.block > div.d4 > div#d5 > a
div.block > div.d4 > div#d6 > a div.block > div.d4 > div#d6 > a
div.part1 > div.list > div.item > a div.part1 > div.list > div.item > a
div.part1 > div.list > div.item > a div.part1 > div.list > div.item > a
div.part1 > div.list > div.item > a div.part1 > div.list > div.item > a
div.part1 > div.list > div.item > a div.part1 > div.list > div.item > a
div.footer > div.part2 > div.logo > a div.footer > div.part2 > div.logo > a

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.

Best practices

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.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
head > meta head > meta

These items highlight common accessibility best practices.

Navigation

A value greater than 0 implies an explicit navigation ordering. Although technically valid, this often creates frustrating experiences for users who rely on assistive technologies. Learn more about the `tabindex` attribute.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
学生|教职工|校友|访客|招聘|捐赠 门户网络邮箱燕云直播图书馆医学部领导信箱 北大概况招生学部与院系教育教学科学研究合作交流校园生活 EN 北大 · 要闻 … body > div.body_b

These are opportunities to improve keyboard navigation in your application.

○Interactive controls are keyboard focusable
○Interactive elements indicate their purpose and state
○The page has a logical tab order
○Visual order on the page follows DOM order
○User focus is not accidentally trapped in a region
○The user's focus is directed to new content added to the page
○HTML5 landmark elements are used to improve navigation
○Offscreen content is hidden from assistive technology
○Custom controls have associated labels
○Custom controls have ARIA roles
●`[aria-*]` attributes match their roles
●`[aria-hidden="true"]` is not present on the document `<body>`
●`[role]`s have all required `[aria-*]` attributes
●`[role]` values are valid
●`[aria-*]` attributes have valid values
●`[aria-*]` attributes are valid and not misspelled
●ARIA attributes are used as specified for the element's role
●`[aria-hidden="true"]` elements do not contain focusable descendents
●Elements use only permitted ARIA attributes
●Background and foreground colors have a sufficient contrast ratio
●Document has a `<title>` element
●Touch targets have sufficient size and spacing.
●Document has a main landmark.
●Deprecated ARIA roles were not used
●The page contains a heading, skip link, or landmark region
●Identical links have the same purpose.
○`[accesskey]` values are unique
○`button`, `link`, and `menuitem` elements have accessible names
○Elements with `role="dialog"` or `role="alertdialog"` have accessible names.
○ARIA input fields have accessible names
○ARIA `meter` elements have accessible names
○ARIA `progressbar` elements have accessible names
○`[role]`s are contained by their required parent element
○Elements with the `role=text` attribute do not have focusable descendents.
○ARIA toggle fields have accessible names
○ARIA `tooltip` elements have accessible names
○ARIA `treeitem` elements have accessible names
○Buttons have an accessible name
○`<dl>`'s contain only properly-ordered `<dt>` and `<dd>` groups, `<script>`, `<template>` or `<div>` elements.
○Definition list items are wrapped in `<dl>` elements
○ARIA IDs are unique
○No form fields have multiple labels
○`<frame>` or `<iframe>` elements have a title
○Heading elements appear in a sequentially-descending order
○`<html>` element has a valid value for its `[lang]` attribute
○`<html>` element has an `[xml:lang]` attribute with the same base language as the `[lang]` attribute.
○Input buttons have discernible text.
○`<input type="image">` elements have `[alt]` text
○Form elements have associated labels
○Links are distinguishable without relying on color.
○Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`).
○List items (`<li>`) are contained within `<ul>`, `<ol>` or `<menu>` parent elements
○The document does not use `<meta http-equiv="refresh">`
○`<object>` elements have alternate text
○Select elements have associated label elements.
○Skip links are focusable.
○Cells in a `<table>` element that use the `[headers]` attribute refer to table cells within the same table.
○`<th>` elements and elements with `[role="columnheader"/"rowheader"]` have data cells they describe.
○`[lang]` attributes have a valid value
○`<video>` elements contain a `<track>` element with `[kind="captions"]`
○Tables have different content in the summary attribute and `<caption>`.
○All heading elements contain content.
○Uses ARIA roles only on compatible elements
○Image elements do not have `[alt]` attributes that are redundant text.
○Elements with visible text labels have matching accessible names.
○Tables use `<caption>` instead of cells with the `[colspan]` attribute to indicate a caption.
○`<td>` elements in a large `<table>` have one or more table headers.
96

Best Practices

General

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

Why this matters

Performance issues directly impact user engagement and conversion rates.

SourceDescription
www.pku.edu.cn/Public/static/themes/image/bg5.svg
Failed to load resource: the server responded with a status of 404 (Not Found)
www.pku.edu.cn/Public/static/themes/image/bg14.svg
Failed to load resource: the server responded with a status of 404 (Not Found)
●Uses HTTPS
●Avoids deprecated APIs
●Avoids third-party cookies
●Allows users to paste into input fields
●Avoids requesting the geolocation permission on page load
●Avoids requesting the notification permission on page load
●Displays images with correct aspect ratio
●Serves images with appropriate resolution
●Page has the HTML doctype
●Properly defines charset
●No issues in the `Issues` panel in Chrome Devtools
●Ensure CSP is effective against XSS attacks
●Use a strong HSTS policy
●Ensure proper origin isolation with COOP
●Mitigate clickjacking with XFO or CSP
●Mitigate DOM-based XSS with Trusted Types
●Detected JavaScript libraries
●Page has valid source maps
○Redirects HTTP traffic to HTTPS
82

SEO

These checks ensure that your page is following basic search engine optimization advice. There are many additional factors Lighthouse does not score here that may affect your search ranking, including performance on Core Web Vitals. Learn more about Google Search Essentials.

Crawling and Indexing

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 how to make links crawlable

Why this matters

Performance issues directly impact user engagement and conversion rates.

Uncrawlable Link
div.slick-slide > div > div.child > a.a1 div.slick-slide > div > div.child > a.a1
div#slick-slide01 > div > div.child > a.a1 div#slick-slide01 > div > div.child > a.a1
div#slick-slide05 > div > div.child > a.a1 div#slick-slide05 > div > div.child > a.a1
div.slick-slide > div > div.child > a.a1 div.slick-slide > div > div.child > a.a1
div.slick-slide > div > div.child > a.a1 div.slick-slide > div > div.child > a.a1
div.slick-slide > div > div.child > a div.slick-slide > div > div.child > a
div.slick-slide > div > div.child > a div.slick-slide > div > div.child > a
通知公告 div.l > div.title > div.fz40 > a.now
北大声明 div.l > div.title > div.fz40 > a
div#slick-slide30 > div > div.child > a div#slick-slide30 > div > div.child > a
div.slick-slide > div > div.child > a div.slick-slide > div > div.child > a

To appear in search results, crawlers need access to your app.

Content Best Practices

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.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
div.inner > div.l > a > img div.inner > div.l > a > img

Format your HTML in a way that enables crawlers to better understand your app’s content.

○Structured data is valid
●Page isn’t blocked from indexing
●Document has a `<title>` element
●Document has a meta description
●Page has successful HTTP status code
●Links have descriptive text
●Document has a valid `hreflang`
○robots.txt is valid
○Document has a valid `rel=canonical`

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