waitFor as a Promise

waitFor.js

function waitFor(testFx, onReady, timeOutMillis) {
	return new Promise(function (resolve, reject) {
		var maxtimeOutMillis = timeOutMillis ? timeOutMillis : 3000,
			start = new Date().getTime(),
			condition = false,
			interval = setInterval(function() {
				if ((new Date().getTime() - start < maxtimeOutMillis) && !condition) {
					condition = (typeof(testFx) === "string" ? eval(testFx) : testFx());
				} else {
					if(!condition) {
						reject(new Error("'waitFor()' timeout"));
					} else {
						resolve(typeof(onReady) === "string" ?eval(onReady) :onReady());
						clearInterval(interval);
					}
				}
			}, 250);
	});
};