Gadget-SpoilerWarning.js

Note: After publishing, you may have to bypass your browser's cache to see the changes.

Firefox / Safari: Hold Shift while clicking Reload, or press either Ctrl-F5 or Ctrl-R (⌘-R on a Mac)
Google Chrome: Press Ctrl-Shift-R (⌘-Shift-R on a Mac)
Internet Explorer / Edge: Hold Ctrl while clicking Refresh, or press Ctrl-F5
Opera: Press Ctrl-F5.

/* Script for Template:Spoiler */

$(function() {
	$('.spoiler-overlay').click(function () {
		$(this).parent().removeClass('spoiler-hidden');
		$(this).remove();
	});
});

MediaWiki:Gadget-SpoilerWarning.js