var username = document.getElementById('username');
    var password = document.getElementById('password');
    var password2 = document.getElementById('password-2');
    var re = /^\w{3,10}$/;
    var len = password.value.length;
    if(re.test(username.value) && len >= 6 && len <= 20 && password.value === password2.value){
        return true;
    }
    alert('用户名或密码不正确！')
    return false;