bug: quitters not getting marked as quitters, and non-quitters get marked as quitters

[deargle]

Logic that has been around for almost a decade has been flagging participants as quitters and then asking them to confirm that they want to quit. If they choose to stay, they're still flagged as quitters. This probably actually doesn't matter though, because if participants get to the end of the experiment after attempting to quit, the /complete route changes their status from "quit" to "complete".

psiTurk/psiturk/psiturk_js/psiturk.js

Lines 277 to 287 in 822d088

	$(window).on("beforeunload", function(){
	self.saveData();
	$.ajax("quitter", {
	type: "POST",
	data: {uniqueId: self.taskdata.id}
	});
	//var optoutmessage = "By leaving this page, you opt out of the experiment.";
	//alert(optoutmessage);
	return "By leaving or reloading this page, you opt out of the experiment. Are you sure you want to leave the experiment?";
	});

Besides that, the current method of returning a string doesn't reliably trigger a confirmation prompt in all browsers. MDN suggests using beacon instead. Edit: meaning that quitters don't always get marked as such, because currently, the POST won't always trigger.