Firing a Keyboard Event in JavaScript

Did you dispatch the event correctly?

function simulateKeyEvent(character) {
  var evt = document.createEvent("KeyboardEvent");
  (evt.initKeyEvent || evt.initKeyboardEvent)("keypress", true, true, window,
                    0, 0, 0, 0,
                    0, character.charCodeAt(0)) 
  var canceled = !body.dispatchEvent(evt);
  if(canceled) {
    // A handler called preventDefault
    alert("canceled");
  } else {
    // None of the handlers called preventDefault
    alert("not canceled");
  }
}

If you use jQuery, you could do:

function simulateKeyPress(character) {
  jQuery.event.trigger({ type : 'keypress', which : character.charCodeAt(0) });
}

I am working on DOM Keyboard Event Level 3 polyfill . In latest browsers or with this polyfill you can do something like this:

element.addEventListener("keydown", function(e){ console.log(e.key, e.char, e.keyCode) })

var e = new KeyboardEvent("keydown", {bubbles : true, cancelable : true, key : "Q", char : "Q", shiftKey : true});
element.dispatchEvent(e);

//If you need legacy property "keyCode"
// Note: In some browsers you can't overwrite "keyCode" property. (At least in Safari)
delete e.keyCode;
Object.defineProperty(e, "keyCode", {"value" : 666})

UPDATE:

Now my polyfill supports legacy properties "keyCode", "charCode" and "which"

var e = new KeyboardEvent("keydown", {
    bubbles : true,
    cancelable : true,
    char : "Q",
    key : "q",
    shiftKey : true,
    keyCode : 81
});

Examples here

Additionally here is cross-browser initKeyboardEvent separately from my polyfill: (gist)

Polyfill demo

This is due to a bug in Webkit.

You can work around the Webkit bug using createEvent('Event') rather than createEvent('KeyboardEvent'), and then assigning the keyCode property. See this answer and this example.

The Mozilla Developer Network provides the following explanation:

1. Create an event using event = document.createEvent("KeyboardEvent")
2. Init the keyevent

using:

event.initKeyEvent (type, bubbles, cancelable, viewArg, 
       ctrlKeyArg, altKeyArg, shiftKeyArg, metaKeyArg, 
           keyCodeArg, charCodeArg)

3. Dispatch the event using yourElement.dispatchEvent(event)

I don't see the last one in your code, maybe that's what you're missing. I hope this works in IE as well...

I am not very good with this but KeyboardEvent => see KeyboardEvent is initialized with initKeyEvent .
Here is an example for emitting event on <input type="text" /> element

document.getElementById("txbox").addEventListener("keypress", function(e) {
  alert("Event " + e.type + " emitted!\nKey / Char Code: " + e.keyCode + " / " + e.charCode);
}, false);

document.getElementById("btn").addEventListener("click", function(e) {
  var doc = document.getElementById("txbox");
  var kEvent = document.createEvent("KeyboardEvent");
  kEvent.initKeyEvent("keypress", true, true, null, false, false, false, false, 74, 74);
  doc.dispatchEvent(kEvent);
}, false);

<input id="txbox" type="text" value="" />
<input id="btn" type="button" value="CLICK TO EMIT KEYPRESS ON TEXTBOX" />