Javascript/requestAnimationFrame

	const SCREEN_SIZE_W = 256;
const SCREEN_SIZE_H = 224;

let can = document.getElementById("can");
let con = can.getContext("2d");

can.width = SCREEN_SIZE_W;
can.height = SCREEN_SIZE_H;

let frameCount = 0;

let chImg = new Image();
chImg.src = "sprite.png";
//chImg.onload = draw;

function update(){

}

function draw(){
    con.fillStyle = "#66aaff";
    con.fillRect(0,0,SCREEN_SIZE_W,SCREEN_SIZE_H);
    con.drawImage(chImg, 0, 0, 16, 32, 100, 10, 64, 128);

    con.font = "24px 'Impact'";
    con.fillStyle = "#fff";
    con.fillText("FRAME:" + frameCount, 10, 20);
}

//setInterval(mainLoop, 1000/60);
window.onload = function(){
    mainLoop();
}
function mainLoop(){
    frameCount++;
    update();
    draw();
    requestAnimationFrame(mainLoop);
}