JQuery :: How To Change Action Attribute Of Forms

I want to change the action attribute of certain forms. I am new to JQuery so I wrote this code but it doesn't work at all:
<script type="text/javascript">
$(document).ready(function(){
$("form").not("form[action*=/nxpages/index.xhtml]").each(function(){
alert("Cat1!");
});
$("form[action*=/nxpages/index.xhtml]").each(function(){
alert("Cat2!");
});
})
</script>
But it seems that JQuery doesnt work at all. How can I change the above code to modify the action value to something else?