Measure todomvc selectall

gistfile1.js

var toggleAll=document.querySelector("#toggle-all");

var allCheckboxes = document.querySelectorAll("ul input[type=checkbox]");
var firstCheckbox = allCheckboxes[0];
var lastCheckbox = allCheckboxes[allCheckboxes.length-1];

waitFor = !toggleAll.checked;
console.log("Wait until "+waitFor);
var startTime = new Date();
toggleAll.click();
var endTime = new Date();
if (firstCheckbox.checked == waitFor) {
	console.log("Done synchronously in "+(endTime-startTime)+"ms");
	alert("Took "+(endTime-startTime)+"ms");
} else {
	console.log("Synchronous part done in "+(endTime-startTime)+"ms. Waiting for async part");
	var timer = setInterval(function() {
		if (firstCheckbox.checked == waitFor) {
			endTime = new Date();
			window.alert("Took "+(endTime-startTime)+"ms (async)");
			console.log("Done asynchronously in "+(endTime-startTime)+"ms");
			clearInterval(timer);
		} else {
			console.log("Still waiting");
		}
	},1)
}