<!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>
<body>
<div id="content">
<div class="name" data-age="1"><span class="age"></span></div>
<div class="name" data-age="2"><span class="age"></span></div>
<div class="name" data-age="3"><span class="age"></span></div>
<div class="name" data-age="4"><span class="age"></span></div>
<div class="name" data-age="5"><span class="age"></span></div>
</div>
<script>
var content = document.getElementById('content'); // 获取父元素
var names = content.getElementsByClassName('name'); // 获取子元素
for (var i = 0; i < names.length; i++) { // 循环遍历
var age = names[i].getAttribute('data-age'); // 获取data-age的值
names[i].getElementsByClassName('age')[0].innerHTML = age * 5; // 获取span元素并赋值
}
</script>
</body>
</html>