Add class when leaving page

action.js

//make sure downloads open in another page with target="_blank"
//"beforeunload" is fired any time a link is clicked. 
//If the link points to a file to download, the user won't be actually leaving the page, but beforeunload will still have fired.

(function () {
	var unload = {};
	unload.init = function () {
		//cache html element
		unload.$html = $(document.documentElement);

		//attach event
		$(window).on('beforeunload', unload.unloading);
	}
	
	unload.unloading = function (e) {
		unload.$html.addClass('unloading');

		//set fallback
		setTimeout(unload.failed, 3000);
	}
	
	//useful if the user comes back, the loading fails, or it takes way too long
	unload.failed = function () {
		unload.$html.removeClass('unloading');
	}
	
	//set this whole thing up on DOMready
	$(unload.init);
	return unload;
})();

animation.css

.unloading .element-to-animate {
	animation: fade-out 1s;
}

This is great, thanks!

So nice, thanks !