javascript - 如何获取 javascript 对象(例如 window)的数字或字符串值而不是字符串 [object]

Question

如何获取 javascript 对象(例如 window)的数字或字符串值而不是字符串 [object]

寻找对象 ID 之类的东西，例如该对象唯一的 44001 或 0xFF0012

Answer 1

Javascript 不会为每个对象保留类似 python 的唯一哈希值。您可以创建一个函数来为对象分配一个唯一的字符串，或者检索已分配的字符串。

var getUniqueId = (function(){

  // uncomment this block if you want to avoid memory leaks
  // in browsers with crappy garbage collectors.
  /*
  try {
    window.addEventListener('unload', cleanup);
    window.addEventListener('beforeunload', cleanup);
  } catch (_) { try {
    window.attachEvent('onunload', cleanup);
    window.attachEvent('onbeforeunload', cleanup);
  } catch (__){}}

  function cleanup () { guid.knownObjects.length=0; }
  */

  guid.knownObjects=[];

  return guid;

  function guid (obj) {
    for (var i=guid.knownObjects.length; i--;) {
      if (guid.knownObjects[i][0]===obj) return guid.knownObjects[i][1];
    }
    var uid='x'+(+(''+Math.random()).substring(2)).toString(32);
    guid.knownObjects.push([obj, uid]);
    return uid;
  }

}());

测试:

getUniqueId(window)
> "x7onn8ne58ug"

getUniqueId(document)
> "x9jeriqjdf9o"

getUniqueId(document)
> "x9jeriqjdf9o"

getUniqueId(window)
> "x7onn8ne58ug"

您可以执行 console.dir(getUniqueId.knownObjects) 以获得一些有用的调试信息。

getUniqueId.knownObjects
> [
  Array
  0: DOMWindow
  1: "x7onn8ne58ug"
  , 
  Array
  0: HTMLDocument
  1: "x9jeriqjdf9o"
  ]