var re_username = /\w{3,10}/;
    var re_password = /\w{6,20}/;

    var input_username = document.getElementById('username')
    var input_pwd = document.getElementById('password');
    var input_pwd2 = document.getElementById('password-2');

    if (re_username.test(input_username.value) === false)
    {
        alert('用户名必须是3-10位英文字母或数字')
        return false;
    }
    if (re_password.test(input_pwd.value) === false)
    {
        alert('密码必须是6-20位英文字母或数字')
        return false;
    }
    if (input_pwd.value !== input_pwd2.value)
    {
        alert('两次输入口令不一致')
        return false;
    }

    return ture;
}