keyboard-input-manager.js

function KeyboardInputManager() {
    this.events = {};
  
    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 keybindings
      76: 1,
      74: 2,
      72: 3
    };
  
    document.addEventListener("keydown", function (event) {
      var modifiers = event.altKey || event.ctrlKey || event.metaKey ||
                      event.shiftKey;
      var mapped    = map[event.which];
  
      if (!modifiers) {
        if (mapped !== undefined) {
          event.preventDefault();
          self.emit("move", mapped);
        }
  
        if (event.which === 32) self.restart.bind(self)(event);
      }
    });
  
    var retry = document.getElementsByClassName("retry-button")[0];
    retry.addEventListener("click", this.restart.bind(this));
  
    // Listen to swipe events
    var gestures = [Hammer.DIRECTION_UP, Hammer.DIRECTION_RIGHT,
                    Hammer.DIRECTION_DOWN, Hammer.DIRECTION_LEFT];
  
    var gameContainer = document.getElementsByClassName("game-container")[0];
    var handler       = Hammer(gameContainer, {
      drag_block_horizontal: true,
      drag_block_vertical: true
    });
  
    handler.on("swipe", function (event) {
      event.gesture.preventDefault();
      mapped = gestures.indexOf(event.gesture.direction);
  
      if (mapped !== -1) self.emit("move", mapped);
    });
  };
  
  KeyboardInputManager.prototype.restart = function (event) {
    event.preventDefault();
    this.emit("restart");
  };

  module.export = KeyboardInputManager;