用户名验证

<!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>
        .right{
            color: green;
        }
        .false{
            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.addEventListener('blur',function(){
            if(reg.test(this.value)){
                console.log('正确的');
                span.className = 'right';
                span.innerHTML = '您输入正确';
            }else {
                console.log('错误的');
                span.className = 'false'
                span.innerHTML = '您输入错误';
            }
        })
    </script>
</body>
</html>