Edit in JSFiddle

(function() {
  var requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame ||
                              window.webkitRequestAnimationFrame || window.msRequestAnimationFrame;
  window.requestAnimationFrame = requestAnimationFrame;
})();

var canvas = document.getElementById('canvas');
if (canvas.getContext) {
    
    //inicializar
    
    var draw = function () {
    
        //dibujar
        
        requestAnimationFrame(draw);
    };
    requestAnimationFrame(draw);
}
<body>
    <canvas id="canvas" width="400" height="300"></canvas>
</body>
#canvas {
    background-color:black
}