保存id的元素的变量被存储在哪里？ [英] Where does the variable holding an element with an id get stored?

问题描述

这个问题（ ID可访问元素）指出，如果一个元素有一个id，那么你可以访问它基于该id的变量名。它引起了我的兴趣，正如我在使用Visual Studio 2010开发过程中看到的这个变量一样。我做了一些好奇的测试，结果发现，$ code> document.getElementById（）仍然是比使用变量名称快。所以，我开始试图透过窗口，认为它必须在窗口[idName] 中，在调试中，并使用 console.log （窗口），找不到实际存储变量的位置。

This question ( Element accessible with ID ) points out that if an element has an id then you can access it by variable name based on that id. It intrigued me, as I had seen this variable available when developing using Visual Studio 2010. I did some testing out of curiosity and it turns out that document.getElementById() was still faster than using the variable name. So, I began trying to look through the window, figuring it must be in window["idName"], in debug, and with console.log(window) and could not find where the variable was actually stored.

当html中定义了一个元素 < div id =foo> 它可以在javascript中使用变量 foo （我不是建议使用这个，不好的做法）。该变量存储在哪里？

When an element is defined in html with <div id="foo"> it is available in javascript with the variable foo (I am not suggesting to use this, it is bad practice). Where is that variable stored?

推荐答案

这是非标准的行为。其中（和）如果存储的是实现。

This is non-standard behavior. Where (and if) it is stored is up to the implementation.

使用 Firefox 15 在Linux上，我不得不深入2个原型对象来找到实际的对象。我在这个StackOverflow页面上运行了这个代码，并得到一个 true 结果。

Using Firefox 15 on Linux, I had to go 2 prototype objects deep to find the actual object. I ran this code on this StackOverflow page, and got a true result.

Object.getPrototypeOf(Object.getPrototypeOf(window)).hasOwnProperty("hlogo");

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在Linux上的Chrome中， 。

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In Chrome on Linux, it was one level deep.

Object.getPrototypeOf(window).hasOwnProperty("hlogo");

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我实际上很惊讶的看到它在Firefox，但是由于Chrome跟随微软模式，所以我猜Firefox一定是觉得需要这样做。

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I was actually surprised to see it in Firefox, but since Chrome followed the Microsoft pattern, I guess Firefox must have felt the need to follow suit.

不知道原型链有多深，可以运行一个循环，并将不同的对象添加到数组中，或者只是使用循环中的对象。

If you don't know how deep a prototype chain is, you can run a loop, and add the different objects to an Array, or just work with the objects in the loop.

var protos = [],
    obj = window;

while (Object.getPrototypeOf(obj) !== null) {
    obj = Object.getPrototypeOf(obj);
    protos.push(obj);
}

alert("The object had " + protos.length + " prototype objects");

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