Uncaught TypeError: Cannot read property ‘length’ of undefined

I’m working on a jquery mobile script to get json from my wordpress site but its not displaying anything and returns with a: ‘Uncaught TypeError: Cannot read property ‘length’ of undefined’ error. I know i’m messing up somewhere with parsing the json, but i happen to be a javascript noob. To the guy that both fixes and explains it to me, i thank you.

HTML:
ListView

    <div data-role="page" id="home">
<div data-role="content">
        <div class="example-wrapper" data-iscroll>
            <ul data-role="listview" id="post-list" data-theme="a"></ul>
        </div>
    </div>
</div>

PageView

<div data-role="page" id="headline">
 <div data-role="content">
        <ul data-role="listview" id="post-data" data-theme="a"></ul>
    </div>
    </div>

JavaScript:

 $(document).on('pageinit', '#home', function () {

                   $.ajax({
                          url: 'http://chris.floppytron.com/api/get_recent_posts/',
                          dataType: "jsonp",
                          success: function (result) {
                          ajax.parseJSONP(result);
                          },
                          error: function (request, error) {
                          alert('Network error has occurred please try again!');
                          }
                          });
                   });

                   $(document).on('pagebeforeshow', '#headline', function () {
                                  $('#post-data').empty();
                                  $.each(postInfo.result, function (i, row) {
                                         if (row.id == postInfo.id) {
                                         $('#post-data').append('<li>' + row.title + '</li>');
                                         $('#post-data').append('<li>' + row.date + '</li>');
                                         $('#post-data').append('<li>' + row.categories + '</li><br />');
                                         $('#post-data').append('<li>' + row.content + '</li>');
                                         $('#post-data').listview('refresh');
                                         }
                                         });
                                  });

                                  $(document).on('vclick', '#post-list li a', function () {
                                                 postInfo.id = $(this).attr('data-id');
                                                 $.mobile.changePage("#headline", {
                                                                     transition: "slide",
                                                                     changeHash: false
                                                                     });
                                                 });

                                                 var postInfo = {
                                                     id: null,
                                                     result: null
                                                 }

var ajax = {
    parseJSONP: function (result) {
        postInfo.result = result.results;
        $.each(result.results, function (i, row) {
               console.log(JSON.stringify(row));
               $('#post-list').append('<li><a href="" data-id="' + row.id + '"><img src="' + row.thumbnail + '"/><h3>' + row.title + '</h3><p>' + row.categories + '</p><br /><p>' + row.date + '</p></a></li>');
               });
               $('#post-list').listview('refresh');
    }
}