a canvas that fills the whole browser window

window-canvas.js

$(document).ready(function(){
  
  // create canvas the size of the window
	var canvasHeight = $(window).height();
	var canvasWidth = $(window).width();
	
	$('body').prepend('<canvas id="canvas" width="'+ canvasWidth +'" height="'+ canvasHeight + '" style="cursor:crosshair;">Your browser doesn\'t support canvas. Boo-hiss.</canvas>');
	
	// resize canvas if window size changes - I particularly don't like this, but whatevs floats yo boats...
	$(window).resize(function() {
		var canvasHeight = $(window).height();
		var canvasWidth = $(window).width();
		$('#canvas').attr('width', canvasWidth).attr('height', canvasHeight);
	});
	
});