JS変数タイプ
1458 ワード
typeof
1、number
:1.
-Infinity( ) "number"
0 "number"
NaN "number"
eg:
var num = 20;
console.log(typeof num);
//
num = 3.14;
console.log(num);
num = -3/0;
//Infinity
console.log(num,typeof num);
num = 0/3;
console.log(num,typeof num);
num = 0/0;
console.log(num,typeof num);
2、boolean
2 true/false;
console.log(5 > 3);
console.log(5 < 3);
3、string
string
:
var english = 'Hello';
var chinese = ' , !!';
var jp = "の";
console.log(english,typeof english,chinese,typeof chinese,jp,typeof jp);
4、null
:
var obj = null;
console.log(obj);
5、undefined undefined
:
var x;
console.log(x, typeof x);
console.log(y);//y is not defined
6、object
:
:
var arr = [1, 2, 3];
var obj = {'userName': ' '};
console.log(obj, typeof obj);
console.log(arr, typeof arr);
7.
=:
var num = 20;
==:
var num = 20;
var num1 = '20';
console.log(num == num1);
===: ( )
js :
:
var num = 20;
console.log(num, typeof num);//number
num = 'の';
console.log(num, typeof num);//string