Paginated jQuery Result Set from XML File Problem_问答_开发者

I am having a spot of bother with a code I am developing to show 10 Magazines at a time that is being fed from an xml file. I have it working to some extent, FF and IE7+8 do not like it, maybe as it says there is an error on line 62 - being the core function calling the data to be fed in.

Here is my code:

<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta name="robots" content="noindex, nofollow" />
<title>Brave Creative - Online Archive</title>
<link rel="stylesheet" href="css/global.css" media="screen" />
<script type="text/javascript" charset="UTF-8" src="js/jquery.js"></script>
<script type="text/javascript">

$(document).ready(function() {

 $.ajax({
    type: "GET",
    url: "issues.xml",
    dataType: "xml",
    success: function(xml) {

    var shelf = $('#shelf-items');
                var startIndex = 0; 
                var howMany = 10; 
                var $issues = $(xml).find('issue'); 
                var totalIssues = $issues.length;
    var numPages = Math.ceil(totalIssues / howMany)

    $('span.issuecount').html(+totalIssues+'&nbsp;Issues - '+numPages+'&nbsp;Pages');

                var displayIssues = function() {
                      var $issuesPaginated = $issues.slice( startIndex , (totalIssues - startIndex) + howMany );
                      $('#shelf-items li').fadeOut(500); 
                      $issuesPaginated.each(function(){
                          var id = $(this).attr('id');
                          var date = $(this).find('date').text();
                          var cover = $(this).find('cover').text();
                          var issue = $(this).find('issuenumber').text();
                          var url = $(this).find('url').text();
                          $('<li id="'+id+'"></li>').html('<a href="'+url+'"><img src="images/covers/'+cover+'" alt="" /></a><br />'+date+' - #'+issue+'').fadeIn(500).appendTo(shelf);
                      });
                }

                $('#prevIssueButton').click(function() {
                    if( startIndex < howMany) {
                        startIndex -= howMany;
                        displayIssues();
                    }else {
      startIndex = 0;
                        displayIssues();
      $('span.error').html('No Issues to Display - You are now on Page 1').fadeIn(300).fadeOut(3000);
                    }
                });
                $('#nextIssueButton').click(function() {
      if( startIndex + howMany <= totalIssues) {
                        startIndex += howMany;
                        displayIssues();
                    }else {
      $('span.error').html('No Issues to Display - You are now on Page 1').fadeIn(300).fadeOut(3000);
                        startIndex = 0;
                        displayIssues();

                    }
                });
                displayIssues().fadeIn(500); 
            }
   }); // end ajax call

}); // end document-ready

</script>
</head>
<body>

<div id="bc-publish"><span></span></div>

<br />

<div id="wrapper">

 <header>
  <h1>Online Archive: <span>FSM</span></h1>
 </header>开发者_如何学编程

    <section id="buttons">

     <a href="#" id="prevIssueButton" title="Toggle Previous Entries">Previous</a>
        <a href="#" id="nextIssueButton" title="Toggle Next Entries">Next</a>

        <span class="error"><a></a></span>

        <div class="clear"></div>

    </section> <!-- /buttons -->

    <section id="shelf">

     <ul id="shelf-items"></ul>

        <div class="clear"></div>

    </section> <!-- /shelf -->
    <br />
    <span class="issuecount"></span>

    <br /><br />

    <span class="logo"><a href="http://www.bravecreative.co.uk" title="Brave Creative"><img src="images/brave-creative-logo.jpg" alt="Brave Creative" /></a></span>
    <span class="address">

     <span>t.</span> 01733 392978 <span>m.</span> 07719442825<br />
  <span>e.</span> tony@bravecreative.co.uk<br />
        4 Milnyard Square, Orton Southgate, Peterborough PE2 6CX

    </span>

    <div class="clear"></div>

</div> <!-- /wrapper -->

</body>
</html>

The previous and next buttons do not work correctly, for instance I click next and I go to page 2, click next again - its blank, and click one last time I get told I have no more results to view. But if i click previous to start of with and go back 3 times (to the start again) then click next I can cycle back up to the same issue, this has really baffled me, any help would be deeply appreciated!

Just reading your code I have a few remarks.

This:

$('span.issuecount').html(+totalIssues+'&nbsp;Issues - '+numPages+'&nbsp;Pages');

Should be without the '+' before 'totalIssues', or am I missing something?

$('span.issuecount').html(totalIssues+'&nbsp;Issues - '+numPages+'&nbsp;Pages');

The end of

$('<li id="'+id+'"></li>').html('<a href="'+url+'"><img src="images/covers/'+cover+'" alt="" /></a><br />'+date+' - #'+issue+'').fadeIn(500).appendTo(shelf);

seems to do things in the wrong order, isn't it? First fade and then appendTo?

This

$('#prevIssueButton').click(function() {
                if( startIndex < howMany) {
                    startIndex -= howMany;
                    displayIssues();

looks strange too, if startIndex indeed is less than howMany, then the startIndex will be negative after this call, is that intended?

Then I'm not sure it's a good idea to have all the code in the success event handler for the Ajax call. I would have separated these thing somewhat, but maybe you have tried that and decided on this. It's just a thought.