canvasで画像を使う

canvas.js

var canvas = document.getElementById('canvas'),
    ctx    = canvas.getContext('2d'),
    image  = new Image();

canvas.setAttribute('width', window.innerWidth);
canvas.setAttribute('height', window.innerHeight);

image.src = 'sample.jpg';

image.addEventListener('load', function() {
  // load完了しないと描画できない
  ctx.drawImage(image, 0, 0);
});