blocks|key|1048393|text|jQuery是用JavaScript编写的。因此，您应该关心JavaScript引擎的速度，因为它也会影响jQuery代码的速度。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1048394|关于如何编写更高效的jQuery代码，有很多技巧和技巧。主要原则是了解jQuery如何工作，如何将选择器转换为从DOM中选择元素的查询，等等。|1048395|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

jQuery is written in JavaScript. So you should care about the speed of the JavaScript engine as it also affects the speed of your jQuery code.

There are plenty of tips and tricks about how to write more efficient jQuery code. The main principle is to understand how jQuery works, how the selectors are translated into queries that select the elements from the DOM and so on.

blocks|key|1033703|text|尽可能地使用原生Javascript方法而不是jQuery方法，您通常会注意到速度有了很大的提高，尤其是在IE中。IE的JS呈现引擎是SLLLOOOOWWW，与其他不太吸引人的浏览器相比。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1033704|例如，我有一个AJAX脚本，它在FF/Safari中运行良好，但在IE中运行起来就像冻结的糖蜜一样。结果，编写它的开发人员大量使用jQuery的$.each()方法从一个大型JSON文件中获取数据。我重写了脚本以使用标准的JS+for()循环，然后对它进行了一些速度测试，结果表明使用for()要快20倍以上。|1033705|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Try to use native Javascript methods instead of jQuery methods whenever possible and you'll generally notice a substantial speed improvement, especially in IE. IE's JS rendering engine is SLLLOOOOWWW compared to other non-sucky browsers.

For example, I had an AJAX script that was running fine in FF/Safari but ran like frozen molasses in IE. Turns out the developer that wrote it made heavy use of jQuery's $.each() method to get data from a large JSON file. I rewrote the script to use standard JS for() loops instead, and running a few speed tests on it afterwards showed that using for() was over TWENTY times faster.

blocks|key|1033576|text|是的，但你不应该纠结于它:)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1033577|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Yes, but you shouldn't obsess over it :)

blocks|key|1047309|text|我从未遇到过使用JQuery或插件(跨浏览器兼容性、非常有用的功能)的好处因速度下降而被忽略的情况。我有时会处理相当大的网页。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1047310|不管怎样，你要知道的唯一方法就是试一试。一开始以最明智的方式编写代码。如果它太慢，那么您可以寻找优化它。|1047311|优化DOM遍历|offset|length|style|BOLD|1047312|http://www.learningjquery.com/2006/12/quick-tip-optimizing-dom-traversal|1047313|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|7|0|0|20|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|U|8|@$F|V|G|W|H|I]]|9|@]|A|$]]|$1|J|3|K|5|6|7|X|8|@]|9|@$F|Y|G|Z|1|10]]|A|$]]|$1|L|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|M|$N|$5|O|P|Q|A|$R|K]]]]

I have not run into a single instance where the benefits of using JQuery or a plugin (cross-browser compatibility, hugely useful functionality) are outweighed by decreases in speed. And I work with pretty large web pages sometimes.

Anyway, the only way you are going to know is to try it. Write your code in the most sensible way possible at first. If it is too slow, then you can look to optimize it. 

Optimizing DOM Traversal 
<a href="http://www.learningjquery.com/2006/12/quick-tip-optimizing-dom-traversal" rel="nofollow noreferrer">http://www.learningjquery.com/2006/12/quick-tip-optimizing-dom-traversal</a>

blocks|key|1033643|text|Contains可能比较慢，因为我不认为文档模型是以任何方式根据元素中出现的文本进行索引的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1033644|但是，我不确定为了优化而过度设计和优化是明智的。如果您有问题，可以选择最简单的方法，进行测试，然后进行优化。|1033645|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Contains might be relatively slow, as I don't believe the document model is indexed in any way by what text appears inside the elements.

However, I'm not sure it's wise to try to overengineer something and optimize for optimizings sake. Go for the simplest thing that works, test, and then optimize if you have a problem.

blocks|key|2560406|text|不，您不应该关心它，因为它不应该影响您编写代码的方式。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2560407|也就是说，您应该始终编写高效的Javascript，因为这只是一个很好的实践，而且对于大多数站点来说，您不知道任何特定用户正在运行的浏览器是什么，所以您可以假设最坏的情况。|2560408|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

No, you shouldn't care about it, because it shouldn't affect how you write code. 

That is to say, you should ALWAYS write efficient Javascript, both because it's just good practice, and because for most sites you have no idea what browser any particular user is running, so you may as well assume the worst.

blocks|key|1047359|text|是的，您应该关心，但幸运的是，jQuery团队同样关心：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1047360|最近对jQuery内部结构的更改(请参阅最后两张幻灯片)|offset|length|1047361|entityMap|0|LINK|mutability|MUTABLE|url|http://www.slideshare.net/jeresig/recent-changes-to-jquerys-internals^0|0|0|S|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@$D|P|E|Q|1|R]]|A|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|G|$H|$5|I|J|K|A|$L|M]]]]

Yes you should be concerned, but luckily, the jQuery Team is just as concerned:

<a href="http://www.slideshare.net/jeresig/recent-changes-to-jquerys-internals" rel="nofollow noreferrer">Recent Changes to jQuery Internals (Check out last two slides)</a>

blocks|key|1047388|text|不要过分优化，但尽可能多地优化。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1047389|如果速度很慢，那么您真的别无选择，只能进去帮助jquery。但如果不是，那何必费心呢。|1047390|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Don't over optimize, but optimize as much as you need to.

If it's slow, then you really have no choice but to go in there and help jquery out. But then if it's not, then why bother.

I'm writing jQuery for a page that is a complex mess of many DOM elements (I have no control over this). The primary target browser is IE7, and I have concerns about the speed of its JavaScript engine. Scripts I've already written are laggy and have been performance-tuned to the best of my ability.

I could write script that is simple to maintain and understand, for example using a single <a href="http://docs.jquery.com/Selectors/contains" rel="nofollow noreferrer"><code>contains</code></a> statement. Or I can help out the engine by narrowing down the DOM search through this messy HTML resulting in more complexity.

Should I care about the speed of the browser's JavaScript engine when writing jQuery scripts?

Should I care about JavaScript engine speed when using jQuery?

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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我正在为一个包含许多DOM元素的复杂混乱的页面编写，(我对此没有控制权)。主要的目标浏览器是IE7，我担心它的JavaScript引擎的速度。我已经写过的脚本是滞后的，并且已经尽我最大的能力进行了性能调整。我可以编写易于维护和理解的脚本，例如使用单个语句。或者，我可以通过这个混乱的HTML缩小DOM搜索范围，从而帮助引擎实现更多的复杂性。在编写JavaScript脚本时，我应该关心浏览器的jQue

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