Making shipping address fields mirror billing fields if the “Use billing address for shipping address” checkbox is checked.

<script type="text/javascript">
jQuery(document).ready(function($) {
$("#fc_form_checkout input").blur(function() {
if (!$("#use_different_addresses").is(":checked")) {
var names = ["first_name","last_name","company","address1","address2","city","state_name","postal_code","phone"];
for (var i in names) {
$("#shipping_"+names).val($("#customer_"+names).val());
}
}
});
 
});
</script>

• http://forum.foxycart.com/comments.php?DiscussionID=3756