是否使用delegate（） [英] To use delegate() or not

问题描述

是否有人可能能够解释为什么使用诸如

Is there someone who might be able to explain why using a function such as

$('#potato').delegate('.frenchFry', 'click', function(e){
    // do something...
});

优于

$('#potato').bind('click', function(e){
    if($(e.target).hasClass('frenchFry'){
        // do something...
    }
});

假设一大片在一个非常动态且不断变化的#potato上的代表团数量是否有使用委托的速度优势（不是我可以提出的任何测试）？

assuming a large number of delegations on a very dynamic and constantly changing #potato? is there a speed advantage to using delegate (not from any tests i could come up with)?

推荐答案

因为 e.target 将引用所点击的最深层嵌套元素，这可能没有您正在寻找的类。

Because e.target will refer to the most deeply nested element clicked, which may not have the class you're looking for.

<div class="frenchFry>
    <span>some nested text</span>
</div>

$(e.target).hasClass('frenchFry') // click on the <span> will return "false"

如果你确定实际的 e.target 将永远是你想要的元素，那么这不会是一个问题。

If you're certain that the actual e.target will always be the element you intend, then this won't be an issue.

使用基于 .delegate（）的选择器测试的不仅仅是 e。目标本身只是让它变得更有活力。

Having a selector based .delegate() that tests more than just the e.target itself simply makes it a little more dynamic.

编辑：顺便说一句，你可以排序复制 .delegate（）这样的事情：

By the way, you could sort of replicate .delegate() something like this:

var node = e.target;

while( node && !$(node).is('.frenchFry') ) {
    node = node.parentNode;
    if( node === this || node === document.body ) {
        node = null;
        break;
    }
}

if( node ) {
    // do something
}

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