经常使用javascript类型判断

//判断是否是数组
console.log(Object.prototype.toString.apply([])==='[object Array]')
//判断是否是函数
console.log(Object.prototype.toString.apply(function(){})==='[object Function]')
//判断是否是null
console.log(Object.prototype.toString.apply(null)==='[object Null]')
//判断是否是undefined
console.log(Object.prototype.toString.apply(undefined)==='[object Undefined]');
//判断是否是字符串
console.log(Object.prototype.toString.apply('str')==='[object String]')