不使用form提交

<div class="container-fluid">
    <div class="row">
        <div class="col-md-8 col-md-offset-2">
            <h1 class="text-center">登录</h1>
            <div class="form-group">
                <label for="id_username">用户名</label>
                <input type="text" name="username" id="id_username" class="form-control">
            </div>
            <div class="form-group">
                <label for="id_password">密码</label>
                <input type="password" name="password" id="id_password" class="form-control">
            </div>
            <div class="form-group">
                <label for="">验证码</label>
                <div class="row">
                    <div class="col-md-6">
                        <input type="text" name="code" id="id_code" class="form-control">
                    </div>
                    <div class="col-md-6">
                        <!--这个页面只要一加载出来，就会朝这个/get_code/路径发get请求-->
                        <img src="/get_code/" alt="" width="430px" height="35px" id="id_img">
                    </div>
                </div>
            </div>
            <input type="button" class="btn btn-success" value="登陆" id="id_commit">
            <span style="color: red;font: bold 16px 微软雅黑" id="error"></span>
        </div>
    </div>
</div>