Can't find form on returned HTML

I have a main page consisting of a link and a div with id 'containerDiv'. When you press the link it loads some HTML from another page using Ajax into this div.

The HTML that is returned contains a form. When the form is submitted, I wish to stay on the same page and display the resulting content in the div.

Please see a picture showing what I wish to accomplish by clicking this link.

The script on the main page:

<script type="text/javascript">
    $(document).ready(function () {
        $("a").click(function () {
            $('#containerDiv').load(this.href + ' #contentDiv', function () {
                alert($('#page2Form').id);
                $('#page2Form').submit(function () {
                    $.post(
                    pageName,
                    this.serialize(),
                    function (data) {
                        if (data.success)
                            alert('done');
                        else
                            alert('error');
                        $('#containerDiv').html(data);
                    }
                );
                    return false;
                });开发者_运维技巧
            });
            return false;
        });
    });
</script>

The relevant HTML on the main page:

<a id="link1" href="page1.aspx">Page 1</a>
    <br />
    <div id='console' style="border: 2px solid red; width: 1000px">
        when the link is clicked this content is replaced with new html.
    </div>

The relevant HTML on the content page:

    <div id="contentDiv">
        <form id="page2Form" runat="server">
        <div>
            <h1>
               Page 2</h1>
            <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
            <asp:Button ID="Button1" runat="server" Text="submit" OnClick="Submit_OnClick" />
        </div>
        </form>
    </div>

The problem is that I can't find the form 'page2Form' on the returned HTML.

Alert ($('#page2Form'). id); returns 'undefined'

Perhaps it has something to do with that element is not loaded in the DOM.

A few things here, jQuery objects won't have a .id property, you want the id of the first element in the matched set, like this:

alert($('#page2Form')[0].id);
//or without jquery:
alert(document.getElementById('page2Form').id);

Also, make sure you're looking for it after the $('#containerDiv').html(data); call, so it's added to the DOM. If you're looking for it before it's added, then use the returning data as the context to look in, like this:

alert($('#page2Form', data)[0].id);