JavaScript isDOM - 如何检查JavaScript对象是否为DOM对象？ [英] JavaScript isDOM -- How do you check if a JavaScript Object is a DOM Object?

问题描述

我试图得到：

document.createElement('div')  //=> true
{tagName: 'foobar something'}  //=> false

在我自己的脚本中，我以前只是使用这个，因为我从来没有需要 tagName 作为属性：

In my own scripts, I used to just use this since I never needed tagName as a property:

if (!object.tagName) throw ...;

所以对于第二个对象，我想出了以下作为一个快速的解决方案 - 大多数工作。 ;）

So for the second object, I came up with the following as a quick solution -- which mostly works. ;)

问题是，这取决于执行只读属性的浏览器，这不是全部。

The problem is, it depends on browsers enforcing read-only properties, which not all do.

function isDOM(obj) {
  var tag = obj.tagName;
  try {
    obj.tagName = '';  // Read-only for DOM, should throw exception
    obj.tagName = tag; // Restore for normal objects
    return false;
  } catch (e) {
    return true;
  }
}

有没有好的替代品？

推荐答案

这可能是有意义的：

function isElement(obj) {
  try {
    //Using W3 DOM2 (works for FF, Opera and Chrom)
    return obj instanceof HTMLElement;
  }
  catch(e){
    //Browsers not supporting W3 DOM2 don't have HTMLElement and
    //an exception is thrown and we end up here. Testing some
    //properties that all elements have. (works on IE7)
    return (typeof obj==="object") &&
      (obj.nodeType===1) && (typeof obj.style === "object") &&
      (typeof obj.ownerDocument ==="object");
  }
}

它是 DOM，Level2

更新2 ：这是我在自己的库中实现的：
（以前的代码在Chrome中不起作用，因为Node和HTMLElement是函数，而不是预期的对象，该代码在FF3，IE7，Chrome 1和Opera 9中进行测试）

Update 2: This is how I implemented it in my own library: (The previous code didn't work in Chrome because Node and HTMLElement are functions instead of the expected object. This code is tested in FF3, IE7, Chrome 1 and Opera 9)

//Returns true if it is a DOM node
function isNode(o){
  return (
    typeof Node === "object" ? o instanceof Node : 
    o && typeof o === "object" && typeof o.nodeType === "number" && typeof o.nodeName==="string"
  );
}

//Returns true if it is a DOM element    
function isElement(o){
  return (
    typeof HTMLElement === "object" ? o instanceof HTMLElement : //DOM2
    o && typeof o === "object" && o !== null && o.nodeType === 1 && typeof o.nodeName==="string"
);
}

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