Async Without Promise

function doAsyncTask(callback: () => void): void {
	setTimeout(() => {
		console.log('Async task done');
		callback();
	}, 1000);
}

function onComplete(): void {
	console.log('Callback executed');
}

doAsyncTask(onComplete);

Version WITH promise:

function doAsyncTask(): Promise<void> {
	return new Promise((resolve) => {
		setTimeout(() => {
			console.log('Async task done');
			resolve();
		}, 1000);
	});
}

function onComplete(): void {
	console.log('Promise resolved');
}

doAsyncTask().then(onComplete);