var name = document.getElementById('username').value;
    var pass = document.getElementById('password').value;
    var re_pass = document.getElementById('password-2').value;
    var nametest = /[A-Za-z0-9]{3,10}/;
    var passtest = /.{6,20}/;
    if (!nametest.test(name)){
        alert('用户名必须是3-10位英文字母或数字，请重新输入');
        return false;
    }
    if (!passtest.test(pass)){
        alert('口令必须是6-20位，请重新输入');
        return false;
    }
    if (pass !== re_pass){
        alert('两次输入口令必须一致，请重新输入');
        return false;
    }
}