jQuery Javascript Tutorial: Check All / Uncheck All Checkboxes

<script language="javascript" src="js/jquery.js"></script>

<img id="checkallboxes" src="img/check_all_boxes.gif" alt="" />
<input id="target_item[]" class="checkbox1" name="target_item[]" type="checkbox" value="myval01" /> My Value 01
<input id="target_item[]" class="checkbox1" name="target_item[]" type="checkbox" value="myval02" /> My Value 02
<input id="target_item[]" class="checkbox1" name="target_item[]" type="checkbox" value="myval03" /> My Value 03
<input id="target_item[]" class="checkbox1" name="target_item[]" type="checkbox" value="myval04" /> My Value 04
<input id="target_item[]" class="checkbox1" name="target_item[]" type="checkbox" value="myval05" /> My Value 05 
 
<!-- This is the jQuery part. It will check all boxes with classname that is equal to checkbox1 -->
<script type="text/javascript"><!--
$(document).ready(function(){
    $(".checkallboxes").toggle(                    //this is the gif file id
    function() {
        $('.checkbox1').attr('checked','checked'); //add the atrribute checked
    },
    function () {
        $('.checkbox1').removeAttr("checked");     //remove the attribute checked
    });
});
--></script>