Simulate a key press using native javascript

I am trying to simulate keyboard commands inside my application. Currently I can press the arrow keys and I can capture events well. However, I am trying to simulate key events, but I have no luck.

Here is my code:

  //Event
  this.remoteEvent = function(arg_event) {
    var e = document.createEvent('KeyboardEvent');
    var method = (typeof e.initKeyboardEvent !== 'undefined') ? "initKeyboardEvent" : "initKeyEvent";

    switch (arg_event) {
      case 'up':
        e[method]('keydown', true, true, window, false, false, false, false, 0, 38);
        break;
      case 'right':
        e[method]('keydown', true, true, window, false, false, false, false, 0, 39);
        break;
      case 'down':
        e[method]('keydown', true, true, window, false, false, false, false, 0, 40);
        break;
      case 'left':
        e[method]('keydown', true, true, window, false, false, false, false, 0, 37);
        break;
      case 'enter':
        e[method]('keydown', true, true, window, false, false, false, false, 0, 13);
        break;
    }

    document.dispatchEvent(e);
  }

      

        
        
        
      

    

Am I approaching something wrong? I don't want to use jQuery and be mostly cross-browser compatible.

Edit: here is the event I'm logging before dispatching:

KeyboardEvent {
  altGraphKey: false
  altKey: false
  bubbles: true
  cancelBubble: false
  cancelable: true
  charCode: 0
  clipboardData: undefined
  ctrlKey: false
  currentTarget: null
  defaultPrevented: false
  detail: 0
  eventPhase: 0
  keyCode: 0
  keyIdentifier: "false"
  keyLocation: 0
  layerX: 0
  layerY: 0
  location: 0
  metaKey: true
  pageX: 0
  pageY: 0
  path: NodeList[0]
  repeat: false
  returnValue: true
  shiftKey: false
  srcElement: document
  target: document
  timeStamp: 1410276114922
  type: "keydown"
  view: Window
  which: 0
}

      

        
        
        
      

    

Edit2: Here is my code for capturing events:

document.addEventListener('keydown', key_down_event, false);

//Key down event
function key_down_event(arg_event)
{
  //Ignore all key events if any modifier key is pressed
  if (arg_event.altKey || arg_event.ctrlKey || arg_event.metaKey || arg_event.shiftKey) return;

  //Get the source
  var source = arg_event.target;
  var destination = null;
  var direction = null;
  var escape = false;

  //Switch on key
  switch(arg_event.keyCode)
  {
    case VK_LEFT: direction = 'left'; break;
    case VK_RIGHT: direction = 'right'; break;
    case VK_DOWN: direction = 'down'; break;
    case VK_UP: direction = 'up'; break;
    case VK_ESC: escape = true; break;
  }
  if (!direction && !escape) return;

  arg_event.stopPropagation();
  arg_event.preventDefault();

  console.log(direction);
}