完成注册功能

function fnEnroll() {
    var zcoUname = document.getElementById("zcuname")
    var zcoError = document.getElementById("zcerror_box")
    var zcoUword1 = document.getElementById("zcuword1")
    var zcoUword2 = document.getElementById("zcuword2")

    zcoError.innerHTML = "<br>"
    if (zcoUname.value.length < 6 || zcoUname.value.length > 12) {
        zcoError.innerHTML = "用户名为6到12位";
        return
    } else if( (zcoUname.value.charCodeAt(0) >= 48) && (zcoUname.value.charCodeAt(0) <= 57)){
        zcoError.innerHTML = "用户名首位不能是数字";
        return
    } else for (var i = 0; i < zcoUname.value.length; i++) {
        if ((zcoUname.value.charCodeAt(i) < 48) || (zcoUname.value.charCodeAt(i) > 57) && (zcoUname.value.charCodeAt(i) < 97) || (zcoUname.value.charCodeAt(i) > 122)) {
            zcoError.innerHTML = "用户名只能是字母与数字";
            return
        }
    }

    if ((zcoUword1.value.length < 6) || (zcoUword1.value.length > 20)) {
        zcoError.innerHTML = "密码为6到20位";
        return
    }
    if (zcoUword2.value.length ==0) {
        zcoError.innerHTML = "请再次输入密码";
        return
    }
    if (zcoUword1.value()!=zcoUword2.value()){
        zcoError.innerHTML="两次密码不一致"
        isError=false;
                return isError;
    }
    return isError;
    window.alert("注册成功！！")
}

　　

{% extends 'daohang.html' %}
{% block title %}注册{% endblock %}
{% block head %}
    <link rel="stylesheet" type="text/css" href="{{ url_for('static',filename='css/zhuce.css') }}">
    <script src="{{ url_for('static',filename='js/zhuce.js') }}"></script>
{% endblock %}

{% block main %}
    <div class="box">
        <h2>注册</h2>
        <form action="{{ url_for('zhuce') }}" method="post">
            <div class="input_box">
                <input id="uname" type="text" placeholder="请输入用户名" name="username">
            </div>
            <div class="input_box">
                <input id="upass" type="password" placeholder="请输入密码" name="password">
            </div>
            <div class="input_box">
                <input id="upass1" type="password" placeholder="请再次输入密码">
            </div>
            <div id="error_box"><br></div>
            <div class="input_box">
                <button onclick="fnzhuce()">注册</button>
            </div>
        </form>
    </div>
{% endblock %}

　　

@app.route('/zhuce/', methods=['GET', 'POST'])
def zhuce():
    if request.method == 'GET':
        return render_template('zhuce.html')
    else:
        username = request.form.get('username')
        password = request.form.get('password')
        user = User.query.filter(User.username == username).first()
        if user:
            return 'username existed'
        else:
            user = User(username=username, password=password)
            db.session.add(user)  # 数据库操作
            db.session.commit()
            return redirect(url_for('denglu'))