- op = Object.prototype,
- ostring = op.toString,
- ...
-
- function isFunction(it) {
- return ostring.call(it) === ‘[object Function]‘;
- }
-
- function isArray(it) {
- return ostring.call(it) === ‘[object Array]‘;
- }
最近在看requireJS的源码时，看到上面一段代码，很是好奇，为啥进行类型判断时使用Object.prototype.toString? 如果是我的话就直接用typeof得了，后来查阅了一些资料：
typeof
- 在使用 typeof 运算符时采用引用类型存储值会出现一个问题，无论引用的是什么类型的对象，它都返回 "object"。
ECMA 对Object.prototype.toString的解释
- Object.prototype.toString ( )
-
- When the toString method is called, the following steps are taken:
-
- If the this value is undefined, return "[object Undefined]".
- If the this value is null, return "[object Null]".
- Let O be the result of calling ToObject passing the this value as the argument.
- Let class be the value of the [[Class]] internal property of O.
- Return the String value that is the result of concatenating the three Strings "[object ", class, and "]".
- var oP = Object.prototype,
- toString = oP.toString;
-
- console.log(toString.call([123]));
- console.log(toString.call(‘123‘));
- console.log(toString.call({a: ‘123‘}));
- console.log(toString.call(/123/));
- console.log(toString.call(123));
- console.log(toString.call(undefined));
- console.log(toString.call(null));
Object.prototype.toString.call()进行类型判断
原文：http://www.cnblogs.com/xuan52rock/p/4378824.html
