小tips：JS中typeof与instanceof用法

function curFun(){};
var numberType = 123;
var stringType = "123";
var booleanType = false;
var obj = {};
var nullType = null;
var arrayType = [];
var unden;

console.log(typeof curFun); //function

console.log(typeof numberType);//number
console.log(typeof stringType);//string
console.log(typeof booleanType); //boolean

console.log(typeof obj); //object
console.log(typeof nullType); //object
console.log(typeof arrayType); //object

console.log(typeof unden); //undefined

var arr = new Array();
console.log(arr instanceof Array); //true
console.log(arr instanceof Object) //true,因为Array是object的子类
function test(){};
var testInstance = new test();
console.log(testInstance instanceof test); //true

if("undefined" != typeof variable){ 
    if(variable=="abc"){ 
        console.log('成功'); 
    } 
}