内存泄漏

memory allocation : object 创造时

memory free : 当没有 reference 指向该object 时

当浏览器执行时，需要维护来自DOM的大量对象，IE使用自己的垃圾回收机制，而这个机制和javascript不同，这就导致内存泄漏的发生。

内存泄漏
A memory leak in JavaScript most commonly occurs when there are DOM nodes that are not reachable from the page’s DOM tree, but are still referenced by a JavaScript object.

email.message = document.createElement(“div”);
displayList.appendChild(email.message);

And later, you remove the element from the display list:

displayList.removeAllChildren();

As long as

email

exists, the DOM element referenced by message will not be removed, even though it is now detached from the page’s DOM tree.