Simple recursive function that waits for DOM changes, used to wait for embedded-JS generated third party code, when no hook apparent or available

waiter.js

function waiter(selector, callback, timeout) {
	var elem = document.querySelectorAll(selector);

	if (!elem.length) {
		if (timeout === undefined) {
			timeout = 100;
		}

		setTimeout(function(){
			waiter(selector, callback, timeout);
		}, timeout);
	} else {
		if (callback) {
			callback(elem);
		}
	}
}