var username = document.getElementById('username');
var password = document.getElementById('password');
var password_2 = document.getElementById('password-2');

var usernameReg = /^\w{3,10}$/;

function checkRegisterForm() {
    var name = username.value.trim();
    if (!usernameReg.test(name)) {
        alert('用户名必须是3-10位英文字母或数字');
        return false;
    }
    var pass = password.value.trim();
    if (pass.length < 6 || pass.length > 20) {
        alert('口令必须是6-20位');
        return false;
    }

    var pass2 = password_2.value;
    if (pass !== pass2) {
        alert('两次输入口令必须一致');
        return false;
    }
    return true;
}