<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>
<script>
var age=prompt("请输入年龄");
if(age>=18){
if(age<=24){
alert("年轻");
}else if(age<=35){
alert("还年轻");
}else{
alert("不年轻");
}
}else{
alert("小孩");
}
</script>
</body>
</html>
