This is a simple starter for working with canvas.

CanvasStarter.js

/*
  Created by Nate Perry
  http://github.com/nateperry
*/

var App;

App = {
  canvas: null,
  ctx: null,
  init : function () {
    App.addEventListeners();
    App.setupCanvas();
  },
  addEventListeners : function () {
    window.onresize = App.onResize;
  },
  onResize : function () {
    App.resizeCanvas();
  },
  setupCanvas : function () {
    App.canvas = document.getElementById('canvas');
    App.ctx = App.canvas.getContext('2d');
    App.resizeCanvas();
  },
  resizeCanvas : function () {
    App.canvas.height = window.innerHeight;
    App.canvas.width = window.innerWidth;
  }
};

window.onload = App.init;