Step 6 for creating a Snake on SSaurel's Blog

gameloop.js

gameloop(timestamp) {
    // Calculate the number of seconds passed since the last frame
    secondspassed = (timestamp - oldtimestamp) / 1000;
    oldtimestamp = timestamp;

    // Calculate fps
    realfps = Math.round(1 / secondspassed);

    if (this.keyup) {
        this.dirx = 0;
        this.diry = -1;
    } else if (this.keydown) {
        this.dirx = 0;
        this.diry = 1;
    } else if (this.keyleft) {
        this.dirx = -1;
        this.diry = 0;
    } else if (this.keyright) {
        this.dirx = 1;
        this.diry = 0;
    }

    now = window.performance.now();
    elapsed = now - then;

    if (elapsed > this.fpsinterval) {
        // Get ready for next frame by setting then=now, but also adjust for your
        // specified fpsInterval not being a multiple of RAF's interval
        then = now - (elapsed % this.fpsinterval);

        this.move();
        this.draw(realfps);
    }

    var self = this;

    window.requestAnimationFrame(function (timestamp) {
        self.gameloop(timestamp);
    });
}