javascript长度属性

Question

return 0['toString']['length'];

为什么它会返回1

Answer 1

1000['toString']给你函数对象Number.prototype.toString,在JS中,函数对象有一个属性length,它返回函数所用的参数个数.在这种情况下是1因为Number.prototype.toString收到基数参数.

alert(Number.prototype.toString.length) // 1

参考文献:

• https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function/Length
• https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Number/toString