views:

689

answers:

4

Anyone know why the following JQuery expression works in Firefox but not in IE or Chrome?

$('form :hidden:last').attr('name')

An alert statement reveals that in IE the expression is undefined.

UPDATE: Here is some HTML that fails.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"&gt;
<html>
   <head>
      <script type="text/javascript" src="/js/jquery-1.3.2.min.js">
      </script>
      <script type="text/javascript">
         function addItem() {
           var v = $('form :hidden:last').attr('name');
           var n = /(.*)input/.exec(v);
           var newPrefix;
           if ( n[1].length == 0 ) {
             newPrefix = '1';
           } else {
             newPrefix = parseInt(n[1])+1;
           }
           var lastExercise = $('form tr:last select:first').attr('value');
           var oldElem = $('form tr:last');
           var newElem = oldElem.clone(true);
           var lastHidden = $('form :hidden:last');
           lastHidden.val(newPrefix);
           var pat = '=\"'+n[1]+'input';
           newElem.html(newElem.html().replace(new RegExp(pat, 'g'), '=\"'+newPrefix+'input'));
           newElem.appendTo('table');
           $('form tr:last select:first').attr('value', lastExercise);
           $('form :hidden:last').val('');
         }
         function removeItem() {
           var rows = $('form tr');
           if ( rows.length > 2 ) {
             rows.filter(":last").remove();
             $('form :hidden:last').val('');
           } else {
             alert('Cannot remove any more rows');
           }
         }
      </script>
   </head>
   <body>
         <form autocomplete="off" method="post" action="">
            <div>
               <input type="button" onclick="addItem(); return false;" value="Add Item" />
               <input type="button" onclick="removeItem(); return false;" value="Remove Last Item" />
            </div>
            <table>
               <tr>
                  <th>Name</th>
                  <th>Weight</th>
               </tr>
               <tr>
                  <td>
                     <input type="text" name="input1" id="input1" value="" />
                  </td>
                  <td>
                     <input type="text" name="input2" id="input2" value="" />
                     <select name="input3" class="unitsInput">
                        <option value="0">
                           Pounds
                        </option>
                        <option value="1">
                           Kilograms
                        </option>
                     </select>
                  </td>
                  <td>
                     <input type="hidden" name="input4" id="input4" value="" />
                  </td>
               </tr>
            </table>
            <div>
               <select name="input8">
                  <option value="0">0</option>
                  <option value="1">1</option>
                  <option value="2">2</option>
               </select>
            </div>
            <div>
               <input type="submit" name="submit" id="submit" value="Submit" />
            </div>
         </form>
   </body>
</html>
A: 

I was able to get it to run fine in IE7.
What does your HTML look like?

Here is what mine looks like:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt;
<html xmlns="http://www.w3.org/1999/xhtml"&gt;
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>Untitled Document</title>
<script type="text/javascript" src="jquery-1.3.2.min.js"></script>
</head>

<body>
<form action="" method="get" name="testform">
<input name="bob" type="hidden" value="" />
<input name="steve" type="hidden" value="" />
<input name="william" type="hidden" value="" /></form>
<script type="text/javascript">
    $(document).ready(function(){
     alert($('form :hidden:last').attr('name'));
    });
</script>
</body>
</html>
Dan Appleyard
My HTML is complex. I was also using IE6. I'll try to find a simple example HTML that fails.
Khanpo
+1  A: 

Do you run this query after DOM is fully loaded and using the latest version of jQuery? The above example from Dan works fine even in IE6 for me.

esycat
+2  A: 

Is your JQuery wrapped in the a $(document).ready( ... ) ?

For example:

$(document).ready(function() {
    $('form :hidden:last').attr('name')
});

It is essential to do this to ensure that the DOM has fully loaded before your JQuery code starts executing. Otherwise, there is no DOM (document) for it to query.

Soviut
A: 

It appears that IE treats the option elements at the end as hidden. Changing all the "...:hidden..." selectors in the javascript to "...input:hidden..." seems to solve the problem.

Khanpo