04.JavaScript数据类型转换

01.字符串拼接

02.bool

03.未定义类型和null

04.获取数据类型

05.数据类型转换

var  a=100;
a+="基地的";
console.log(typeof a+":"+a)
var b=100;
console.log(typeof b.toString()+":"+b)
var c=500;
c=String(c);
console.log(typeof c+":"+c)      

var a="444.22";
a=parseInt(a);
console.log(a)
var b="666.22";
b=parseFloat(b);
console.log(b)
var c="999.22";
b=Number(c);
console.log(c) //999.22
var d='454';
d=d-1;
console.log(d) //453
console.log(typeof d) //number