WordPress: Fade in last sidebar widget

frontend.js

jQuery(document).ready(function($) {
	/**
	* Configuration
	* The container for your sidebar e.g. aside, #sidebar etc.
	*/
	var sidebarElement = $('div#secondary');
	// End config

	// Check if the sidebar exists
	if ($(sidebarElement).length > 0) {
		// Get the last widget in the sidebar, and its position on screen
		var widgetDisplayed = false;
		var lastWidget = $('.widget:last-child', $(sidebarElement));
		var lastWidgetOffset = $(lastWidget).offset().top;
		
		// Hide the last widget
		$(lastWidget).hide();
		
		// When the user scrolls, check if we have reached the top of the last widget
		// If we have, display the widget
		$(document).scroll(function() {
			// If the widget has been displayed, we don't need to keep doing
			// a check.
			if (!widgetDisplayed) {
				if($(this).scrollTop() > lastWidgetOffset) {
				    $(lastWidget).fadeIn('slow');
				    widgetDisplayed = true;  
			    }
		    }
		});
	}
});