js中的typeof和instanceof和===
typeof:
用于判断number/string/boolean/underfined类型/function
不能判断:null和object ,不能区分object和Array
instanceof:
判断具体的对象类型
===:
用于判断undefined和null
//五种基本类型 var num=1; var str="abc"; var bl=true; var nu=null; var undef=undefined; //三种特殊类型 var obj=new Object(); var arr2=["1",2,true]; var fun=function () { } write("-------typeof-----------") write(num,typeof num);//1 number write(str,typeof str);//abc string write(bl,typeof bl);//true boolean write(nu,typeof nu);//null object write(undef,typeof undef)//undefined undefined write(obj,typeof obj);//[object Object] object write(arr2,typeof arr2);//1,2,true object write("-----------===-----------") write(num,typeof num==="number");//1 true write(str,typeof str==="string");//abc true write(bl,typeof bl==="boolean");//true true write(nu,typeof nu==="object");//null true write(undef,typeof undef==="undefined")//undefined true write(obj,typeof obj==="object");//[object Object] true write(arr2,typeof arr2==="object");//1,2,true true write(fun,typeof fun==="function");//function () { } true write("---------instanceof---------------") write(obj,obj instanceof Object)//[object Object] true write(arr2,arr2 instanceof Array);//1,2,true true write(arr2,arr2 instanceof Object);//1,2,true true write(fun, fun instanceof Function)//function () { } true write(fun, fun instanceof Object)//function () { } true