blocks|key|393836|text|这取决于浏览器：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|393837|393838|安卓浏览器，火狐和火狐手机在window.onload之后启动预取请求，但Chrome和Opera会立即启动它们，可能会窃取当前页面所需的更重要资源的TCP连接。|blockquote|393839|393840|393841|从IE11开始，各个网络请求按类型划分优先级，通常按以下顺序排列。|393842|使用onload+event+handlers|393843|Synchronous+stylesheets|unordered-list-item|393844|
|393845|WOFF+(+XHR+)+libraries|393846|393847|Images脚本请求加载的网页的根文档以及使用onload+event+handlers|393848|393849|Synchronous|393850|393851|(XHR)|393852|
脚本请求加载的CSS|393853|+requests|393854|393855|HTML5字体和|393856|393857|脚本(例如indexedDB、Web+Worker、File+API以及使用object+video|393858|393859|Microsoft+element|393860|393861|Deferred+(defer="true")|393862|
加载的|393863|ordered-list-item|393864|+JavaScript+JavaScript和其他控件|393865|393866|上下文也很重要：|393867|393868|+IE11还根据请求的上下文确定请求的优先级：|393869|393870|393871|由前台选项卡中的网页发出的|393872|请求由前台选项卡中的iframe元素中加载的内容发出的请求|393873|请求由后台tabs|393874|Requests+|393875|393876|中的网页发出的请求|393877|参考|offset|length|style|BOLD|393878|393879|Prebrowsing|393880|IE11+Network+Prioritization|393881|Getting+to+the+Content+You+Want,+Faster+in+IE11|393882|Chromium:+New+JavaScript+Techniques+for+Rapid+Page+Loads|393883|‎Chromium:+The+Trace+Event+Profiling+Tool+(about:tracing)‎|393884|Chromium:+Inter-Process+Communication|393885|MDN:+HTML5+Parser|393886|MDN:+Controlling+DNS+Prefetching|393887|MDN:+Tips+for+authoring+fast-loading+HTML+pages|393888|393889|entityMap|0|LINK|mutability|MUTABLE|url|http://www.stevesouders.com/blog/2013/11/07/prebrowsing/|1|https://msdn.microsoft.com/en-gb/library/dn265036|2|http://blogs.msdn.com/b/ie/archive/2013/12/04/getting-to-the-content-you-want-faster-in-ie11.aspx|3|http://blog.chromium.org/2015/03/new-javascript-techniques-for-rapid.html|4|http://www.chromium.org/developers/how-tos/trace-event-profiling-tool/trace-event-reading|5|https://dev.chromium.org/developers/design-documents/inter-process-communication|6|https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/HTML5/HTML5_Parser|7|https://developer.mozilla.org/en-US/docs/Web/HTTP/Controlling_DNS_prefetching|8|https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/Tips_for_authoring_fast-loading_HTML_pages^0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|2|0|0|0|B|0|0|0|R|1|0|0|1B|2|0|0|1K|3|0|0|1M|4|0|0|11|5|0|0|H|6|0|0|W|7|0|0|1B|8|0|0^^$0|@$1|2|3|4|5|6|7|3K|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|3L|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|3M|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|3N|8|@]|9|@]|A|$]]|$1|G|3|-4|5|6|7|3O|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|3P|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|3Q|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|3R|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|3S|8|@]|9|@]|A|$]]|$1|Q|3|R|5|N|7|3T|8|@]|9|@]|A|$]]|$1|S|3|P|5|6|7|3U|8|@]|9|@]|A|$]]|$1|T|3|U|5|N|7|3V|8|@]|9|@]|A|$]]|$1|V|3|P|5|6|7|3W|8|@]|9|@]|A|$]]|$1|W|3|X|5|N|7|3X|8|@]|9|@]|A|$]]|$1|Y|3|P|5|6|7|3Y|8|@]|9|@]|A|$]]|$1|Z|3|10|5|N|7|3Z|8|@]|9|@]|A|$]]|$1|11|3|12|5|6|7|40|8|@]|9|@]|A|$]]|$1|13|3|14|5|N|7|41|8|@]|9|@]|A|$]]|$1|15|3|P|5|6|7|42|8|@]|9|@]|A|$]]|$1|16|3|17|5|N|7|43|8|@]|9|@]|A|$]]|$1|18|3|P|5|6|7|44|8|@]|9|@]|A|$]]|$1|19|3|1A|5|N|7|45|8|@]|9|@]|A|$]]|$1|1B|3|P|5|6|7|46|8|@]|9|@]|A|$]]|$1|1C|3|1D|5|N|7|47|8|@]|9|@]|A|$]]|$1|1E|3|P|5|6|7|48|8|@]|9|@]|A|$]]|$1|1F|3|1G|5|N|7|49|8|@]|9|@]|A|$]]|$1|1H|3|1I|5|6|7|4A|8|@]|9|@]|A|$]]|$1|1J|3|-4|5|1K|7|4B|8|@]|9|@]|A|$]]|$1|1L|3|1M|5|1K|7|4C|8|@]|9|@]|A|$]]|$1|1N|3|-4|5|6|7|4D|8|@]|9|@]|A|$]]|$1|1O|3|1P|5|6|7|4E|8|@]|9|@]|A|$]]|$1|1Q|3|-4|5|6|7|4F|8|@]|9|@]|A|$]]|$1|1R|3|1S|5|E|7|4G|8|@]|9|@]|A|$]]|$1|1T|3|-4|5|6|7|4H|8|@]|9|@]|A|$]]|$1|1U|3|-4|5|6|7|4I|8|@]|9|@]|A|$]]|$1|1V|3|1W|5|6|7|4J|8|@]|9|@]|A|$]]|$1|1X|3|1Y|5|1K|7|4K|8|@]|9|@]|A|$]]|$1|1Z|3|20|5|1K|7|4L|8|@]|9|@]|A|$]]|$1|21|3|22|5|1K|7|4M|8|@]|9|@]|A|$]]|$1|23|3|-4|5|1K|7|4N|8|@]|9|@]|A|$]]|$1|24|3|25|5|6|7|4O|8|@]|9|@]|A|$]]|$1|26|3|27|5|6|7|4P|8|@$28|4Q|29|4R|2A|2B]]|9|@]|A|$]]|$1|2C|3|-4|5|6|7|4S|8|@]|9|@]|A|$]]|$1|2D|3|2E|5|N|7|4T|8|@]|9|@$28|4U|29|4V|1|4W]]|A|$]]|$1|2F|3|2G|5|N|7|4X|8|@]|9|@$28|4Y|29|4Z|1|50]]|A|$]]|$1|2H|3|2I|5|N|7|51|8|@]|9|@$28|52|29|53|1|54]]|A|$]]|$1|2J|3|2K|5|N|7|55|8|@]|9|@$28|56|29|57|1|58]]|A|$]]|$1|2L|3|2M|5|N|7|59|8|@]|9|@$28|5A|29|5B|1|5C]]|A|$]]|$1|2N|3|2O|5|N|7|5D|8|@]|9|@$28|5E|29|5F|1|5G]]|A|$]]|$1|2P|3|2Q|5|N|7|5H|8|@]|9|@$28|5I|29|5J|1|5K]]|A|$]]|$1|2R|3|2S|5|N|7|5L|8|@]|9|@$28|5M|29|5N|1|5O]]|A|$]]|$1|2T|3|2U|5|N|7|5P|8|@]|9|@$28|5Q|29|5R|1|5S]]|A|$]]|$1|2V|3|-4|5|6|7|5T|8|@]|9|@]|A|$]]|$1|2W|3|-4|5|6|7|5U|8|@]|9|@]|A|$]]]|2X|$2Y|$5|2Z|30|31|A|$32|33]]|34|$5|2Z|30|31|A|$32|35]]|36|$5|2Z|30|31|A|$32|37]]|38|$5|2Z|30|31|A|$32|39]]|3A|$5|2Z|30|31|A|$32|3B]]|3C|$5|2Z|30|31|A|$32|3D]]|3E|$5|2Z|30|31|A|$32|3F]]|3G|$5|2Z|30|31|A|$32|3H]]|3I|$5|2Z|30|31|A|$32|3J]]]]

This is browser dependent:

<blockquote>
 Android browser, Firefox, and Firefox mobile start prefetch requests after window.onload, but Chrome and Opera start them immediately possibly stealing TCP connections from more important resources needed for the current page.
</blockquote>

Starting with IE11, individual network requests are prioritized by type, generally in this order.

<ol>
<li>The root document of the webpage</li>
<li>CSS stylesheets</li>
<li>WOFF fonts</li>
<li>Script libraries</li>
<li>Images loaded using onload event handlers</li>
<li>Synchronous XMLHttpRequest (XHR) requests</li>
<li>Asynchronous script requests (such as indexedDB, Web Workers, File API, and others)</li>
<li>Asynchronous XHR requests</li>
<li>HTML5 audio and video</li>
<li>Microsoft ActiveX and other controls loaded using the object element</li>
<li>Deferred JavaScript (defer="true")</li>
</ol>

The context is also important:

<blockquote>
 IE11 also prioritizes requests based on context of the request:
</blockquote>

<ol>
<li>Requests made by the webpage in the foreground tab</li>
<li>Requests made by content loaded in iframe elements in the foreground tab</li>
<li>Requests made by webpages in background tabs</li>
<li>Requests for pre-rendered content</li>
</ol>

References

<ul>
<li><a href="http://www.stevesouders.com/blog/2013/11/07/prebrowsing/" rel="nofollow">Prebrowsing</a></li>
<li><a href="https://msdn.microsoft.com/en-gb/library/dn265036" rel="nofollow">IE11 Network Prioritization</a></li>
<li><a href="http://blogs.msdn.com/b/ie/archive/2013/12/04/getting-to-the-content-you-want-faster-in-ie11.aspx" rel="nofollow">Getting to the Content You Want, Faster in IE11</a></li>
<li><a href="http://blog.chromium.org/2015/03/new-javascript-techniques-for-rapid.html" rel="nofollow">Chromium: New JavaScript Techniques for Rapid Page Loads</a></li>
<li><a href="http://www.chromium.org/developers/how-tos/trace-event-profiling-tool/trace-event-reading" rel="nofollow">‎Chromium: The Trace Event Profiling Tool (about:tracing)‎</a></li>
<li><a href="https://dev.chromium.org/developers/design-documents/inter-process-communication" rel="nofollow">Chromium: Inter-Process Communication</a></li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/HTML5/HTML5_Parser" rel="nofollow">MDN: HTML5 Parser</a></li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Controlling_DNS_prefetching" rel="nofollow">MDN: Controlling DNS Prefetching</a></li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/Tips_for_authoring_fast-loading_HTML_pages" rel="nofollow">MDN: Tips for authoring fast-loading HTML pages</a></li>
</ul>

This might be a silly question but I want to ask if prefetching resources like js scripts and images slows page load.

eg: If I have a page with a number of these links:

<pre><code>&lt;link rel="prefetch" href="http://example.com/images.png" /&gt;
</code></pre>

Will downloading them be included in the page load time or is prefetching (which using idle browser time) not part of the page load time stats?

Does it truly happen in the background in idle time or is it just another part of the page load?

thanks

HTML Prefetch Resources

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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这可能是一个愚蠢的问题，但我想问的是，预取js、脚本和图像等资源是否会降低页面加载速度。例如:如果我有一个页面，上面有很多这样的链接：<link rel="prefetch" href="http://example.com/images.png" />下载它们是包含在页面加载时间中，还是预取(使用空闲浏览器时间)不是页面加载时间统计的一部分？它是否真的发生在空闲时间的后台，或者只是页面加载的另一

问HTML预取资源
EN

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