Add CSS class with JavaScript

I have the following code that makes check-boxes a little fancier by adding an image sprite to the check-box.

Javascript:

$(document).ready(function() {

    /* see if anything is previously checked and reflect that in the view*/
    $(".checklist input:checked").parent().addClass("selected");

    /* handle the user selections */
    $(".checklist .checkbox-select").click(
        function(event) {
            event.preventDefault();
            $(this).parent().addClass("selected");
            $(this).parent().find(":checkbox").attr("checked", "checked");
        }
    );

    $(".checklist .checkbox-deselect").click(
        function(event) {
            event.preventDefault();
            $(this).parent().removeClass("selected");
            $(this).parent().find(":checkbox").removeAttr("checked");
        }
    );
});

CSS:

.checklist
{
    list-style: none;
    margin: 0;
    padding: 0;
}
.checklist li
{
    float: left;
    margin-right: 10px;
    background: url(resources/i/checkboxbg.gif) no-repeat 0 0;
    width: 105px;
    height: 150px;
    position: relative;
    font: normal 11px/1.3 "Lucida Grande" , "Lucida" , "Arial" ,Sans-serif;
}
.checklist li.selected
{
    background-position: -105px 0;
}
.checklist li.selected .checkbox-select
{
    display: none;
}
.checkbox-select
{
    display: block;
    float: left;
    position: absolute;
    top: 118px;
    left: 10px;
    width: 85px;
    height: 23px;
    background: url(resources/i/select.gif) no-repeat 0 0;
    text-indent: -9999px;
}
.checklist 开发者_运维问答li input
{
    display: block;
}
a.checkbox-deselect
{
    display: none;
    color: white;
    font-weight: bold;
    text-decoration: none;
    position: absolute;
    top: 120px;
    right: 10px;
}
.checklist li.selected a.checkbox-deselect
{
    display: block;
}
.checklist li label
{
    display: block;
    text-align: center;
    padding: 8px;
}

Markup:

<ul class="checklist">  
    <li>
        <asp:CheckBox ID="CheckBox1"  Text="<img src='' />Option" runat="server" />
        <a class="checkbox-select" href="#">Select</a> 
        <a class="checkbox-deselect" href="#">Cancel</a>
    </li>
</ul>

When the check-box is selected, class="selected" is added to the <li>. The trouble is that if the user hits the back button, the check-boxes are still selected (page cached), but the css is not re-applied. I could always add some cache-control so the browser loads a fresh copy of the page each time, so the check boxes will not be checked, but I would rather re-apply the the class to the list item.

Each <ul class="checklist"> is wrapped in an asp.net panel that is rendered as a div with an id of ct100_ContentPlaceHolder1_Panel1 - how would I loop through each check-box in that panel and re-attach the css class if the check-box is checked?

Thanks in advance!

You can do this on load using the :checked selector:

$('.checklist :checked').parent().addClass('selected');