<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
span {
color: #aaa;
font-size: 14px;
}
.right {
color: green;
}
.wrong {
color: red;
}
</style>
</head>
<body>
<input type="text" class="uname"> <span>请输入用户名</span>
<script>
var reg = /^[a-zA-Z0-9_-]{6,16}$/;
var uname = document.querySelector('.uname');
var span = document.querySelector('span');
uname.onblur = function() {
if (reg.test(this.value)) {
// console.log('yes');
span.className = 'right';
span.innerHTML = '用户名输入正确';
} else {
// console.log('no');
span.className = 'wrong';
span.innerHTML = '用户名输入错误';
}
}
</script>
</body>
</html>