这个JavaScript的成语是什么：var self = this？ [英] What underlies this JavaScript idiom: var self = this?

问题描述

我在 WebKit HTML 5 SQL存储说明演示的源中看到了以下内容：

I saw the following in the source for WebKit HTML 5 SQL Storage Notes Demo:

function Note() {
  var self = this;

  var note = document.createElement('div');
  note.className = 'note';
  note.addEventListener('mousedown', function(e) { return self.onMouseDown(e) }, false);
  note.addEventListener('click', function() { return self.onNoteClick() }, false);
  this.note = note;
  // ...
}

作者使用 self 在某些地方（函数体）和这在其他地方（函数参数列表中定义的函数体）。这是怎么回事？

The author uses self in some places (the function body) and this in other places (the bodies of functions defined in the argument list of methods). What's going on? Now that I've noticed it once, will I start seeing it everywhere?

推荐答案

查看此 alistapart.com上的文章

self 用于维护对原始 this 的引用，即使上下文正在更改。这是一种经常用于事件处理程序的技术（特别是在闭包中）。

self is being used to maintain a reference to the original this even as the context is changing. It's a technique often used in event handlers (especially in closures).

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