我可以在jQuery中缓存$(window)和$(document)吗? [英] Can I cache $(window) and $(document) in jQuery?

问题描述

我最近阅读了一些有关jQuery性能的文章，并且提出了一些奇怪的问题.

I recently read some articles regarding jQuery performance, and I came up with some weird questions.

• 我可以/应该缓存$(window)吗?

如果我这样做了，会影响resize，scroll，width，scrollTop ...等吗?

If I did, would it affect resize, scroll, width, scrollTop...etc?

我可以/应该缓存$(document)吗?

由于我们使用了许多鼠标操作，我应该执行var doc = $(document);吗?

As we use a lot of mouse actions, should I do var doc = $(document);?

我可以总是在大量代码中缓存$(this)吗?

Can I always cache $(this) in a big block of code?

对于var self = $(this);，在什么条件下self可能与$(this)不同?

As for var self = $(this);, in what condition that self might be different from $(this)?

推荐答案

所有三个问题:是的，可以！

日用品:否

更好的表现:也许

您可以尝试进行基准测试.但是，缓存的原因不是在整个DOM中搜索您的选择器.查找文档和窗口不是问题，因为它们是2个根变量.缓存$(this)取决于情况.请参阅我的第二个提示.

You could try and do a benchmark. But the reason for caching is not to search entire DOM for your selector. Looking up document and window isn't a problem because they are 2 root variables. Caching $(this) depends on situation. See my 2nd tip.

始终缓存在其上运行查询的父对象:

var header = $('#header');
    
var menu = header.find('.menu');
// or
var menu = $('.menu', header);

链接jQuery方法比缓存选择器更好:

$('li.menu-item').click(function () {alert('test click');})
                     .css('display', 'block')
                     .css('color', 'red')
                     fadeTo(2, 0.7);

缓存经常查询的元素:

var header = $('#header');
var divs = header.find('div');
var forms = header.find('form');

免费的额外性能提示:

选择器的速度最慢:

Id > Tag > classes

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