js作用域.html
525 Bytes
<!DOCTYPE>
<HTML>
<head>
<title>js作用域</title>
<meta name="viewport" content="width=device-width,initial-scale=1,maximum-scale=1,minimum-scale=1,user-scalable=no" />
<style>
*{
margin: 0;
padding: 0;
}
</style>
</head>
<body>
<script>
var a = 12;
function fn(){
console.log('a 1',a)
var a = 24;
console.log('a 2',a)
}
fn();
</script>
<!-- 一、 var 声明的变量，存在变量提升 -->
</body>
</HTML>