Object.prototype.toString.call()

  首先看一段ECMA中对Object.prototype.toString的解释：

Object.prototype.toString( )

When the toString method is called, the following steps are taken:

1. Get the [[Class]] property of this object.

2. Compute a string value by concatenating the three strings “[object “, Result (1), and “]”.

3. Return Result (2)

我们知道，Javascript中，一切皆为对象。所以如下代码，应当会输出对应字符： 

var oP = Object.prototype,
toString = oP.toString;

console.log(toString.call([123]));//[object Array]
console.log(toString.call('123'));//[object String]
console.log(toString.call({a: '123'}));//[object Object]
console.log(toString.call(/123/));//[object RegExp]
console.log(toString.call(123));//[object Number]
console.log(toString.call(undefined));//[object Undefined]
console.log(toString.call(null));//[object Null]

//....

 标准浏览器中完美的作到，但是（为什么要说但是呢）IE6中，却会出现以下问题：

通过Object.prototype.toString.call获取的 字符串,undefined,null均为Object 

所以，我们又要悲剧的先对以上类型进行判断，完整代码： 

var oP = Object.prototype,
toString = oP.toString;

function typeOf(value) {
    if (null === value) {
        return 'null';
    }

    var type = typeof value;
    if ('undefined' === type || 'string' === type) {
        return type;
    }

    var typeString = toString.call(value);
    switch (typeString) {
    case '[object Array]':
        return 'array';
    case '[object Date]':
        return 'date';
    case '[object Boolean]':
        return 'boolean';
    case '[object Number]':
        return 'number';
    case '[object Function]':
        return 'function';
    case '[object RegExp]':
        return 'regexp';
    case '[object Object]':
        if (undefined !== value.nodeType) {
            if (3 == value.nodeType) {
                return (/\S/).test(value.nodeValue) ? 'textnode': 'whitespace';
            } else {
                return 'element';
            }
        } else {
            return 'object';
        }
    default:
        return 'unknow';
    }

}