LessWig

var canvasBg = document.getElementById("canvasBg"),
	ctxBg = canvasBg.getContext("2d"),
	canvasEntities = document.getElementById("canvasEntities"),
	ctxEntities = canvasEntities.getContext("2d"),
	canvasWidth = canvasBg.width,
	canvasHeight = canvasBg.height,
	background = new Background(0, 0),
	spaceship = new Spaceship(0, canvasHeight/2),
	alienShip = new AlienShip(100, 0),
	alienShip2 = new AlienShip(300, 500),