<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<style>
* {
margin: 0;
padding: 0;
}
.header {
display: flex;
height: 50px;
width: 600px;
}
.header li {
text-align: center;
line-height: 50px;
list-style: none;
border: 1px solid red;
flex: 1;
}
.body {
height: 300px;
width: 600px;
position: relative;
}
.body li {
list-style: none;
background-color: aquamarine;
position: absolute;
top: 0;
left: 0;
height: 300px;
width: 600px;
display: none;
}
.body .a1 {
display: block;
}
.a {
background-color: red;
}
</style>
<body>
<ul class="header">
<li class="a">a</li>
<li>b</li>
<li>c</li>
<li>d</li>
</ul>
<ul class="body">
<li class="a1">11</li>
<li>22</li>
<li>33</li>
<li>44</li>
</ul>
<script>
var header_li = document.querySelectorAll('.header li');
var body_li = document.querySelectorAll('.body li');
header_li.forEach(function (item, index) {
item.addEventListener('click', function () {
for (var i = 0; i < header_li.length; i++) {
header_li[i].classList.remove('a');
body_li[i].classList.remove('a1');
}
header_li[index].classList.add('a');
body_li[index].classList.add('a1');
})
})
</script>
</body>
</html>