Run an AJAX call before leaving the page through a link.

ajaxBefore.js

jQuery(".my-awesome-link-class").one('click', function(event){
    var $this = jQuery(this);
	
	//no need to delay when the link opens in a new window
	if (!$this.attr("target") && !event.ctrlKey && !event.shiftKey && !event.metaKey) {
        event.preventDefault();
		var newHref = this.href;
        
        //the below is pseudo-code
        jQuery.ajax({
           success: function(){
                //now go to the URL that the user intended
                document.location.href = newHref;
           } 
        });
	}
});