38 lines
626 B
HTML
38 lines
626 B
HTML
|
<!DOCTYPE html>
|
||
|
<html lang="en">
|
||
|
<head>
|
||
|
<meta charset="UTF-8">
|
||
|
<meta name="viewport" content="width=device-width, initial-scale=1.0">
|
||
|
<title>Document</title>
|
||
|
</head>
|
||
|
<body>
|
||
|
|
||
|
<script>
|
||
|
|
||
|
//js 弱类型
|
||
|
|
||
|
//变量
|
||
|
var a0
|
||
|
var a1= "xxx"
|
||
|
|
||
|
let b0
|
||
|
let b1= "xxx"
|
||
|
|
||
|
const c0= "xxx"//只能赋值
|
||
|
|
||
|
//1.
|
||
|
//在全局变量 var 声名的变量,是挂在window全局对象上的
|
||
|
//在全局变量let 声名的变量,就是全局变量
|
||
|
|
||
|
//2.
|
||
|
//var可以重复声名
|
||
|
//let const 不可以重复声名
|
||
|
|
||
|
//3.
|
||
|
//const声名的是常量 无法修改
|
||
|
|
||
|
|
||
|
</script>
|
||
|
|
||
|
</body>
|
||
|
</html>
|