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js类型判断

js类型有:字符串、数字、布尔、数组、对象、null、undefined。


typeof

console.log(typeof "a"); //stringconsole.log(typeof 1); //numberconsole.log(typeof true); //booleanconsole.log(typeof []); //objectconsole.log(typeof new {}); //objectconsole.log(typeof null); //objectvar a;console.log(typeof a); //undefinedconsole.log(typeof function(){}); //function

从中可以看出typeof对数组、对象、null返回的类型都为object。


Object.prototype.toString.call

var type=Object.prototype.toString;console.log(type.call("a")); //[object String]console.log(type.call(1)); //[object Number]console.log(type.call(true)); //[object Boolean]console.log(type.call([])); //[object Array]console.log(type.call({})); //[object Object]console.log(type.call(null)); //[object Null]var a;console.log(type.call(a)); //[object Undefined]console.log(type.call(function(){})); //[object Function]

 

js类型判断