Use requestAnimationFrame for FUOC-less resolution (#5)

index.js

@@ -8,25 +8,17 @@ module.exports = selector => {
 	}
 
 	const promise = new Promise(resolve => {
-		const el = document.querySelector(selector);
-
-		// Shortcut if the element already exists
-		if (el) {
-			resolve(el);
-			selectorCache.delete(selector);
-			return;
-		}
-
 		// Interval to keep checking for it to come into the DOM
-		const awaitElement = setInterval(() => {
+		(function check() {
 			const el = document.querySelector(selector);
 
 			if (el) {
 				resolve(el);
-				clearInterval(awaitElement);
 				selectorCache.delete(selector);
+			} else {
+				requestAnimationFrame(check);
 			}
-		}, 50);
+		})();
 	});
 
 	selectorCache.set(selector, promise);

test.js

@@ -5,6 +5,7 @@ import m from './';
 
 global.document = jsdom.jsdom();
 global.window = document.defaultView;
+global.requestAnimationFrame = fn => setTimeout(fn, 16);
 
 test('check if element ready', async t => {
 	const elCheck = m('#unicorn');