1、typeof
检测变量string，number，boolean，undefined；
如果变量的值是一个null或者对象，则typeof都会返回object；
如果变量是一个函数，则typeof返回function；
var s = 'teststr'; var n = 435; var b = true; var u; var i = null; var o = new Object();function fnc() {}； console.log(typeof(s)); //string console.log(typeof(n)); //number console.log(typeof(b)); //boolean console.log(typeof(u)); //undefined console.log(typeof(i)); //object console.log(typeof(o));//objectconsole.log(typeof(fnc)); //function
2、instanceof
instanceof 用来判断一个变量是否是某个对象的实例；
var a = new Array(); var fnc = function(){}; function fs() {}; var test = new fs(); console.log(a instanceof Array); //true console.log(a instanceof Object); //true console.log(fnc instanceof Function); //true console.log(fnc instanceof Object); //true console.log(test instanceof Function); //false; console.log(test instanceof fs); //true console.log(test instanceof Object); true
转载于:https://www.cnblogs.com/gengcjun/p/6625550.html
