Example 4-6. Node-style callback

function loadImageNodeStyle(url, callback) {
	var image = new Image();
	image.src = url;
	image.onload = function () {
		callback(null, image);
	};
	image.onerror = function (error) {
		callback(error);
	};
}

loadImageNodeStyle('labyrinth_puzzle.png', function (err, image) {
	if (err) {
		console.log('Unable to load image');
		return;
	}
	console.log('Image loaded');
});