var value2 = 0 ;
var value3 = null ;
var value4 = true ;
var value5 ;
console.log(typeof(value1));
console.log(typeof(value2));
console.log(typeof(value3));
console.log(typeof(value4));
console.log(typeof(value5));
以上代码执行结果是:
var value3 = null ;
var value4 = true ;
var value5 ;
console.log(typeof(value1));
console.log(typeof(value2));
console.log(typeof(value3));
console.log(typeof(value4));
console.log(typeof(value5));
以上代码执行结果是:
number
object
boolean
undefined
切换到console界面
复制你要运行的代码,粘贴回车
你会有惊喜噢
直接运行一次不就好了
var value3 = null ;
var value4 = true ;
var value5 ;
console.log(typeof(value1)); 没有叫value的变量 所以undefined
console.log(typeof(value2)); 0是number
console.log(typeof(value3)); null、undefined、number都是object
console.log(typeof(value4)); true、false是boolean
console.log(typeof(value5)); 定义了变量,没赋值,undefined