JavaScript闭包和内存泄漏 [英] JavaScript Closures and Memory Leaks

问题描述

我在Jquery的Action中读到内存泄漏可能是因为javascript关闭造成的。

I read in Jquery in Action that memory leaks can result from javascript closures.

意外关闭会产生意想不到的后果。例如，循环引用会导致内存一个典型的例子就是创建了DOM元素，这些元素引用了闭包变量，阻止了这些变量的回收。

"Unintended closures can have unintended consequences. For example, circular references can lead to memory leaks. A classic example of this is the creation of DOM elements that refer back to closure variables, preventing those variables from being reclaimed."

有人可以给出一个这样的例子吗？ ？

could somebody give an example of this?

谢谢！

推荐答案

在这里， onClick 有一个闭包，它引用元素。通过将 onClick 分配到 element.click ，创建了一个圆圈：元素 - > onClick - > 元素 - > onClick ...

Here, onClick has a closure which keeps reference to element. By assigning onClick to element.click the circle is created: element -> onClick -> element -> onClick...

function addClickHandler(element) {
    element.click = function onClick(e) {
        alert("Clicked the " + element.nodeName)
    }
}

在某些（大多数？肯定不是所有）javascript引擎中，垃圾收集器不会收集甚至只有一个引用它的对象。即使从DOM中删除元素，上面的循环自引用也会阻止元素和 onClick 被收集，因此内存泄漏。

In some (most? certainly not all) javascript engines the garbage collector will not collect an object that has even a single reference to it. Even if element is removed from the DOM, the circular self-reference above would prevent element and onClick from being collected, thus the memory leak.

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