Function.prototype.bind = Function.prototype.bind || function (target) {    var self = this;    return function (args) {        if (!(args instanceof Array)) {            args = [args];        }        self.apply(target, args);    };};(function () {    if (typeof window.Element === "undefined" ||      "classList" in document.documentElement) {        return;    }    var prototype = Array.prototype,      push = prototype.push,      splice = prototype.splice,      join = prototype.join;    function DOMTokenList(el) {        this.el = el;        // The className needs to be trimmed and split on whitespace        // to retrieve a list of classes.        var classes = el.className.replace(/^\s+|\s+$/g, ‘‘).split(/\s+/);        for (var i = 0; i < classes.length; i++) {            push.call(this, classes[i]);        }    }    DOMTokenList.prototype = {        add: function (token) {            if (this.contains(token)) return;            push.call(this, token);            this.el.className = this.toString();        },        contains: function (token) {            return this.el.className.indexOf(token) != -1;        },        item: function (index) {            return this[index] || null;        },        remove: function (token) {            if (!this.contains(token)) return;            for (var i = 0; i < this.length; i++) {                if (this[i] == token) break;            }            splice.call(this, i, 1);            this.el.className = this.toString();        },        toString: function () {            return join.call(this, ‘ ‘);        },        toggle: function (token) {            if (!this.contains(token)) {                this.add(token);            } else {                this.remove(token);            }            return this.contains(token);        }    };    window.DOMTokenList = DOMTokenList;    function defineElementGetter(obj, prop, getter) {        if (Object.defineProperty) {            Object.defineProperty(obj, prop, {                get: getter            });        } else {            obj.__defineGetter__(prop, getter);        }    }    defineElementGetter(HTMLElement.prototype, ‘classList‘, function () {        return new DOMTokenList(this);    });})();

function KeyboardInputManager() {    this.events = {};    if (window.navigator.msPointerEnabled) {        //Internet Explorer 10 style        this.eventTouchstart = "MSPointerDown";        this.eventTouchmove = "MSPointerMove";        this.eventTouchend = "MSPointerUp";    } else {        this.eventTouchstart = "touchstart";        this.eventTouchmove = "touchmove";        this.eventTouchend = "touchend";    }    this.listen();}KeyboardInputManager.prototype.on = function (event, callback) {    if (!this.events[event]) {        this.events[event] = [];    }    this.events[event].push(callback);};KeyboardInputManager.prototype.emit = function (event, data) {    var callbacks = this.events[event];    if (callbacks) {        callbacks.forEach(function (callback) {            callback(data);        });    }};KeyboardInputManager.prototype.listen = function () {    var self = this;    var map = {        38: 0, // Up        39: 1, // Right        40: 2, // Down        37: 3, // Left        75: 0, // Vim up        76: 1, // Vim right        74: 2, // Vim down        72: 3, // Vim left        87: 0, // W        68: 1, // D        83: 2, // S        65: 3  // A    };    // Respond to direction keys    document.addEventListener("keydown", function (event) {        var modifiers = event.altKey || event.ctrlKey || event.metaKey ||                    event.shiftKey;        var mapped = map[event.which];        // Ignore the event if it‘s happening in a text field        if (self.targetIsInput(event)) return;        if (!modifiers) {            if (mapped !== undefined) {                event.preventDefault();                self.emit("move", mapped);            }        }        // R key restarts the game        if (!modifiers && event.which === 82) {            self.restart.call(self, event);        }    });    // Respond to button presses    this.bindButtonPress(".retry-button", this.restart);    this.bindButtonPress(".restart-button", this.restart);    this.bindButtonPress(".keep-playing-button", this.keepPlaying);    // Respond to swipe events    var touchStartClientX, touchStartClientY;    var gameContainer = document.getElementsByClassName("game-container")[0];    gameContainer.addEventListener(this.eventTouchstart, function (event) {        if ((!window.navigator.msPointerEnabled && event.touches.length > 1) ||        event.targetTouches > 1 ||        self.targetIsInput(event)) {            return; // Ignore if touching with more than 1 finger or touching input        }        if (window.navigator.msPointerEnabled) {            touchStartClientX = event.pageX;            touchStartClientY = event.pageY;        } else {            touchStartClientX = event.touches[0].clientX;            touchStartClientY = event.touches[0].clientY;        }        event.preventDefault();    });    gameContainer.addEventListener(this.eventTouchmove, function (event) {        event.preventDefault();    });