testing keydown events in Jasmine with specific keyCode

Question

I am writing tests for an AngularJS directive which fires events of a <textarea> when certain keys are pressed. It all works fine per my manual testing. I want to be good and have a full unit-test suite too, but I have run into a problem I can't solve on my own:

I want to send a specific keyCode in my triggerHandler() call in my test, but I can't find a way to specify the key that actually works. I am aware of a lot of questions and answers on the topic of building and sending events with specific data, but none of them work on my setup:

My setup

• Karma test runner
• PhantomJS browser running the tests (but also tried Firefox and Chrome without success)
• I'm not using jQuery and I'm hoping there is a regular JS solution. There must be!

Test code

var event = document.createEvent("Events");
event.initEvent("keydown", true, true);
event.keyCode = 40; // in debugging the test in Firefox, the event object can be seen to have no "keyCode" property even after this step
textarea.triggerHandler(event); // my keydown handler does not fire

The strange thing is, I can type the first 3 lines into the console in Chrome and see that the event is being created with the keyCode property set to 40. So it seems like it should work.

Also, when I call the last line like this textarea.triggerHandler("keydown"); it works and the event handler is triggered. However, there is no keyCode to work with, so it is pointless.

I suspect it may be something to do with the nature of the test running against a DOM that is different to a regular page running in the browser. But I can't figure it out!

Answer 1

I've used the following solution to test it and having it working in Chrome, FF, PhantomJS and IE9+ based on this SO answer. It doesn't work in Safari - tried millions of other solution without any success...

function jsKeydown(code){
  var oEvent = document.createEvent('KeyboardEvent');

  // Chromium Hack: filter this otherwise Safari will complain
  if( navigator.userAgent.toLowerCase().indexOf('chrome') > -1 ){
    Object.defineProperty(oEvent, 'keyCode', {
      get : function() {
        return this.keyCodeVal;
      }
    });     
    Object.defineProperty(oEvent, 'which', {
      get : function() {
        return this.keyCodeVal;
      }
    });
  }

  if (oEvent.initKeyboardEvent) {
    oEvent.initKeyboardEvent("keydown", true, true, document.defaultView, false, false, false, false, code, code);
  } else {
    oEvent.initKeyEvent("keydown", true, true, document.defaultView, false, false, false, false, code, 0);
  }

  oEvent.keyCodeVal = code;

  if (oEvent.keyCode !== code) {
    console.log("keyCode mismatch " + oEvent.keyCode + "(" + oEvent.which + ") -> "+ code);
  }

  document.getElementById("idToUseHere").dispatchEvent(oEvent);
}

// press DEL key
jsKeydown(46);

Hope it helps

Update

Today I've found and tested this solution which is offers a much wider coverage of browsers (enabling the legacy support):

https://gist.github.com/termi/4654819

All the credit goes to the author of this GIST. The code does support Safari, PhantomJS and IE9 - tested for the first 2.