Object.prototype.toString.call()
2011-10-27 23:07 sniper007 阅读(472) 评论(0) 编辑 收藏 举报 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]
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';
}
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';
}
}