js/application.js

// boot the game and let the ai handle it
window.requestAnimationFrame(function () {
    var gm = new GameManager(4, KeyboardInputManager, HTMLActuator, LocalStorageManager);

    var aiDelay = 80;
    var aiTimer = null;

    function getCells() {
        var cells = [];
        for (var x = 0; x < 4; x++) {
            cells[x] = [];
            for (var y = 0; y < 4; y++) {
                var t = gm.grid.cells[x][y];
                cells[x][y] = t ? t.value : 0;
            }
        }
        return cells;
    }

    function doMove() {
        if (gm.over) {
            // auto restart after a short pause
            setTimeout(function () {
                gm.storageManager.clearGameState();
                gm.actuator.continueGame();
                gm.setup();
                scheduleNext();
            }, 1500);
            return;
        }

        // keep going past 2048
        if (gm.won && typeof gm.keepPlaying !== "boolean") {
            gm.keepPlaying();
        } else if (gm.won && !gm.keepPlaying) {
            gm.keepPlaying = true;
            gm.actuator.continueGame();
        }

        var cells = getCells();

        fetch("/api/move", {
            method: "POST",
            headers: { "Content-Type": "application/json" },
            body: JSON.stringify({ cells: cells })
        }).then(function (r) { return r.json(); })
            .then(function (data) {
                if (data.direction >= 0) {
                    gm.move(data.direction);
                }
                scheduleNext();
            })
            .catch(function () {
                // server might be busy, retry
                scheduleNext();
            });
    }

    function scheduleNext() {
        aiTimer = setTimeout(doMove, aiDelay);
    }

    // start after a tiny delay so the board renders first
    setTimeout(function () {
        scheduleNext();
    }, 500);
});