<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
</head>
<body>
<script>
var arr=[1,2,3,4,5,6];
arr.slice(1,4);
arr.slice(1,-2);
arr.splice(2,0,'js');
arr
arr.splice(4,2);
arr.splice(2,1,'css');
arr
// 更新分两步完成，先删除再添加
var str='html,css,javascript'
</script>
</body>
</html>
