var checkRegisterForm = function () {
    var username = document.getElementById('username').value
    var password = document.getElementById('password').value
    var password2 = document.getElementById('password-2').value
    re1 = /^\w{3,8}$/
    re2 = /\S{6,20}/
    ans1 = re1.test(username)
    ans2 = re2.test(password)
    if (ans1) {
        if (ans2 && password===password2) {
            return true;
        }
        else if (!ans2) {
            alert('密码不规范');
            return false;
        } else {
            alert('两次输入密码不一致');
            return false;
        }
    }
    alert('用户名不规范');
    return false;
}