jQuery对象:缓存还是不缓存? [英] jQuery object: to cache or not to cache?

问题描述

我的Javascript(JS)代码给我带来了一些麻烦，因为有时我需要在同一函数中多次访问同一DOM元素. 此处

I have some trouble that comes from my Javascript (JS) codes, since I sometimes need to access the same DOM elements more than once in the same function. Some reasoning is also provided here.

从性能的角度来看，一次创建一个jQuery对象然后对其进行缓存是更好的方法，还是随心所欲地创建相同的jQuery对象呢? 示例:

From the point of view of the performance, is it better to create a jQuery object once and then cache it or is it better to create the same jQuery object at will? Example:

function(){
  $('selector XXX').doSomething(); //first call
  $('selector XXX').doSomething(); //second call
  ...
  $('selector XXX').doSomething(); // n-th call
}

或

function(){
  var  obj = $('selector XXX');
  obj.doSomething(); //first call
  obj.doSomething(); //second call
  ...
  obj.doSomething(); // n-th call       
}

我认为答案可能取决于"n"的值，因此假设n是一个小"数字(例如3)，然后是一个中等数字(例如10)，最后是一个大数字(例如30，就像该对象用于for循环中的比较一样.

I suppose that the answer probably depends by the value of "n", so assume that n is a "small" number (e.g. 3), then a medium number (e.g. 10) and finally a large one (e.g. 30, like if the object is used for comparison in a for cycle).

谢谢.

推荐答案

最好缓存元素，如果n大于1，则缓存元素，或将操作链接在一起(您可以对大多数 jQuery操作执行$('#something').something().somethingelse();，因为它们通常会返回包装后的集合本身).顺便说一句，以货币符号$开头的高速缓存变量的命名已经成为一种标准，因此在代码的后期，很明显，您正在对jQuery集执行操作.因此，您会看到很多人先执行var $content = $('#content');然后执行$content.find('...');.

It is always better to cache the element, if n is greater than 1, cache the element, or chain the operations together (you can do $('#something').something().somethingelse(); for most jQuery operations, since they usually return the wrapped set itself). As an aside, it has become a bit of a standard to name cache variables beginning with a money sign $ so that later in the code it is evident that you are performing an operation on a jQuery set. So you will see a lot of people do var $content = $('#content'); then $content.find('...'); later on.

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