JavaScript数据类型

 

/**
 * Created by Jeco on 2018/11/27.
 */

var a
a = 'a'
console.log(typeof (a))
console.log(a)

var num1 =10;
var num2=10;
var sum = num1 + num2 ;
//把sum自动转换成字符串做拼接
console.log("sum =" +sum)

================================================================

var a
a = 'a'
console.log(typeof (a))
console.log(a)

var num1 =10;
var num2=10;
var sum = num1 + num2 ;
console.log("sum =" +sum)

var num3 = Infinity-1
var num4= NaN
console.log(num3)

var a ='123'
var num5=parseInt(a)

=====================================

var str1 = "sunck"
// 字符相加
console.log(str1+"!!")
console.log(typeof(str1))

=============================

var a = "123"

var num = parseInt(a)

console.log(typeof (num))


=================================

var num = parseInt(prompt("qing shuru "))

console.log(num)

var num1 =10;
var num2 = 10;

//先赋值后++
console.log(num1++)
console.log(num1)
++num2
console.log(++num2)
console.log(num2)