Is it possible to change $(window).width() via jQuery, so that something like this is possible:
$(\'#click\').click(function(){
//menu 100px
No it's not. The underlying DOM element itself doesn't support modifying the width of the browser window. It is possible to change the dimensions of the content (outerWidth / innerWidth) area. However I don't believe this has an affect on the size of the window which is what you seem to want to achieve