$(this).serialize()序列化表单，获取不到东西？

Question

1.form表单

  <form class="form-horizontal reginster-form" name="reginster-form" action="{:url('registin')}" method="post">
                <span class="heading">用户注册</span>
                <div class="form-group">
                    <input type="text" class="form-control" id="username" placeholder="用户名">
                    <i class="fa fa-user"></i>
                </div>
                <div class="form-group help">
                    <input type="password" class="form-control" id="password" placeholder="密　码">
                    <i class="fa fa-lock"></i>
                </div>
                <div class="form-group help">
                    <input type="password" class="form-control" id="repassword" placeholder="确认密码">
                    <i class="fa fa-lock"></i>
                </div>
                <div class="form-group">
                    <button type="submit" class="btn btn-primary">注册</button>                  
                </div>
</form>

2.jquery代码

$('form').submit(function() {
          alert($(this).serialize());
          return false;
        });

Answer 1

表单没有name，兄弟你获取不到东西的

Answer 2

input标签，缺乏name属性

Answer 3

表单元素需要加上name属性，这样序列化才能看到值