关于form表单提交的问题

Question

在看金山的网页的源代码时，发现有如下的代码:
<form action="https://my.xoyo.com/login/loginAction/http%3A%2F%2Fwww.xoyo.com%2F" method="post" onsubmit="return verify();" target="login">
                    <fieldset>
                        <legend>填写通行证账号与密码</legend>
                        <div id="warning" class="warning" style="display:none;">
                            
                        </div><!--warning-->
                        <p>
                            <label>通行证：</label>
                            <input type="text" name="name" class="text" id="name" tabindex="1" maxlength="31" value="">
                        </p>
                        <p>
                            <label>密　码：</label>
                            <input type="password" name="pwd" class="text" id="pwd" tabindex="2" maxlength="32">
                            <a class="forget" href="http://my.xoyo.com/find/index/">忘记密码？</a>
                        </p>
                        <p id="scode1">
                            <label>验证码：</label>
                            <input type="text" name="scode" class="text scode" id="scode" tabindex="3">
                            <span><img id="changeScodeImg" src="./金山逍遥Xoyo.com_files/saved_resource" title="换一张"></span>
                            <a id="changeScodeLink" class="changeScode" href="https://my.xoyo.com/login/login/http%3A%2F%2Fwww.xoyo.com%2F####">换一张</a>
                        </p>
                        <p>
                            <input type="hidden" id="passport" name="passport" value="">
                            <input type="image" class="verify" tabindex="4" src="./金山逍遥Xoyo.com_files/login-btn.png" alt="登录">
                        </p>
                    </fieldset>
                </form>里面的提交按钮并没有用input type="submit",而且也没有从其他的javascript代码中看到有bind该登陆按钮的方法，请问这个表单到底是怎样提交的呢？

Answer 1

<input type="image" 也可以提交表单。。

Answer 2

有可能是通过js代码来实现提交的
如：document.forms[0].submit();