Creating a prototype function on a dom element

Creating a prototype function on a dom element

$.fn.customFadeIn = function(fn) { 
    //set opacity to 0 and visibility to visibile
  $(this).css({"opacity" : 0, "visibility" : "visible" });
	$(this).animate({opacity: 1}, 1000, "swing", function(){
		if(typeof fn == 'function')
		  fn.call(this);
	});
};