Step 5 for creating a Snake on SSaurel's Blog

move.js

move() {
    var dirx = this.dirx;
    var diry = this.diry;

    // if the snake eats the food
    if (this.head.x == this.food.x && this.head.y == this.food.y) {
        // add a new tail
        var newtail = { x: this.head.x - dirx, y: this.head.y - diry };
        this.elements.unshift(newtail);
        this.tail = newtail;
        this.food = this.generatefood(this.nbx, this.nby);
        this.points++;

        if (this.points % this.level == 0) {
            this.fps++;
            this.fpsinterval = 1000 / this.fps;
        }
    }

    // if the head touch one part of the elements
    var self = this;
    var touch = false;

    this.elements.every((element) => {
        if (self.head != element && self.head.x == element.x && self.head.y == element.y) {
            touch = true;
            return false;
        }

        return true;
    });

    if (touch) {
        // we restart the game
        this.init();
        return;
    }

    var newx = this.head.x + dirx;
    var newy = this.head.y + diry;

    if (newx >= this.nbx) {
        newx = 0;
    } else if (newx < 0) {
        newx = this.nbx - 1;
    }

    if (newy >= this.nby) {
        newy = 0;
    } else if (newy < 0) {
        newy = this.nby - 1;
    }

    var newhead = { x: newx, y: newy };

    this.elements.shift(); // remove last
    this.elements.push(newhead); // add new head

    this.head = newhead;
}