Keyboard movement and mouse looking

In order to move our camera around, we're going to encapsulate some state, so let's define a KeyboardControls class in a new JavaScript file:

function KeyboardControls(object, options) {
  this.object = object;
  options = options || {};
  this.domElement = options.domElement || document;
  this.moveSpeed = options.moveSpeed || 1;

  this.domElement.addEventListener('keydown', this.onKeyDown.bind(this), false);
  this.domElement.addEventListener('keyup', this.onKeyUp.bind(this), false);
}

KeyboardControls.prototype = {
  update: function() {
    if (this.moveForward)  this.object.translateZ(-this.moveSpeed);
    if (this.moveBackward) this.object.translateZ( this.moveSpeed);
    if (this.moveLeft)     this.object.translateX(-this.moveSpeed);
    if (this.moveRight)    this.object.translateX( this.moveSpeed);
  },
  onKeyDown: function (event) {
    switch (event.keyCode) {
      case 38: /*up*/
      case 87: /*W*/ this.moveForward = true; break;

   ...