JavaScript addEventListener and removeEventListener polyfill for IE6+

EventListenerPolyfill.js

/**
 * Event polyfill 
 * Michael Rouse 
 * December 2016 
 */
function polyfillEvent(e) { 
  e = e || window.event; 

  e.eventPhase = e.eventPhase || 0;
  e.defaultPrevented = e.defaultPrevented || false; 
  e.bubbles = e.bubbles || true; 
  e.cancelable = e.cancelable || true;
  e.view = e.view || undefined; 

  e.preventDefault  = e.preventDefault  || function () { e.returnValue = false; e.defaultPrevented = true; }
  e.stopPropagation = e.stopPropagation || function () { e.cancelBubble = true }
  
  return e;
}


/**
 * addEventListener and removeEventListener Polyfill IE5+
 * Michael Rouse 
 * December 2016
 */
(function() { 
  if (window.addEventListener && window.removeEventListener) return; // Polyfill is not needed :) 
  if (!window.attachEvent || !window.detachEvent) { console.warn("Can't apply polyfill: no attachEvent or detachEvent"); return; }

  var IsFunction = function(toCheck) { return typeof toCheck === 'function'; };
  var Phases = { None: 0, Capturing: 1, AtTarget: 2, Bubbling: 3 };


  /**
   * Add Event Listener 
   */
  function addEventListener(action, callback, capture) { 
    capture = capture ? true : false; 

    var self = this; 

    // Properties that hold the event listeners 
    self.__listeners          = self.__listeners || { };
    self.__listeners[action]  = self.__listeners[action] || [ ];

    // Listener object that will go in the array 
    var listener = {
      fn: callback,
      useCapture: capture
    };

    // Only register the event once 
    if (self.__listeners[action].length == 0) {
      // Create event listener for the first time
      self.__listeners['on' + action] = function(e) { 
        e = polyfillEvent(e);
        
        e.target = e.srcElement || self; 

        var domList = [];
        var node = e.target;

        // Get all nodes for propagation of the event 
        while (node) {
          domList.unshift(node);
          node = node.parentNode; 
        }
        if (domList[0] !== window) domList.unshift(window);

        e.view = domList[0]; // e.view is a reference to the window object where the event was called 
        

        // Capturing Phase (Window -> Target)
        for (var i = 0; i < domList.length; i++) { 
          var el = domList[i];

          e.eventPhase = (self === el) ? Phases.AtTarget : Phases.Capturing;
          e.currentTarget = el; 
          
          if (!el.__listeners || !el.__listeners[action]) continue; // No events on this element 
          

          // Call all the listeners on this element for this action 
          for (var j = 0; j < el.__listeners[action].length; j++) { 
            var listener = el.__listeners[action][j]; 

            if (!listener.useCapture || !IsFunction(listener.fn)) continue; // Ivalid callback or not a capture 

            // Call the event listener 
            listener.fn.call(el, e); 

            // Do not continue if propagation was stopped
            if (e.cancelBubble) return; 
          }
        }


        // Bubbling Phase (Target -> Window)
        for (var i = domList.length - 1; i >= 0; i--) { 
          var el = domList[i]; 

          e.eventPhase = (self === el) ? Phases.AtTarget : Phases.Bubbling; 
          e.currentTarget = el;

          if (!el.__listeners || !el.__listeners[action]) continue; // No event listeners 

          // Call all the listeners on this element for this action 
          for (var j = 0; j < el.__listeners[action].length; j++) { 
            var listener = el.__listeners[action].length; 

            if (listener.useCapture || !IsFunction(listener.fn)) continue; // A capture event or invalid callback 

            // Call the event listener 
            listener.fn.call(el, e);

            // Do not continue if propagation was stopped
            if (e.cancelBubble) return; 
          }
        }        

        e.cancelBubble = true;
      };

      // Use attachEvent to create the event listener
      self.attachEvent('on' + action, self.__listeners['on' + action]);
    }

    // Add the listener to the polyfill
    self.__listeners[action].push(listener);
  }


  /**
   * Remove Event Listener
   */
  function removeEventListener(action, callback, capture) { 
    capture = capture ? true : false; 

    var self = this; 

    // Properties that hold the event listeners 
    self.__listeners = self.__listeners || { };
    self.__listeners[action] = self.__listeners[action] || [];

    // Find the event listener and remove it
    for (var i = 0; i < self.__listeners[action].length; i++) { 
      if (self.__listeners[action][i].fn == callback && self.__listeners[action][i].useCapture == capture) {
          self.__listeners[action].splice(i, 1);
          break;
      }
    }

    // If no more events exist, remove the event listener 
    if (self.__listeners[action].length == 0 && IsFunction(self.__listeners['on' + action])) { 
      self.detachEvent('on' + action, self.__listeners['on' + action]);
    } 
  }

  // Applies the polyfill to an element
  function polyfill(el) { 
    el.addEventListener = addEventListener;
    el.removeEventListener = removeEventListener;

    return el;
  }

  // Alters a function on the document 
  function ReplaceDocFunction(fn) { 
    var old = document[fn];
    document[fn] = function(param) { 
      return polyfill(old(param));
    };
  }

  // Apply the polyfills
  polyfill(window);
  polyfill(document);

  // Add polyfill to window.Element if possible 
  if (window.Element && window.Element.prototype) { 
    polyfill(window.Element.prototype); 
  } else {
    // Apply the polyfill to all of the elements in the document  
    for(var i = 0; i < document.all.length; i++) { 
      polyfill(document.all[i]); 
    }

    // Change these important functions to return something that has the event listener functions
    ReplaceDocFunction('getElementById');
    ReplaceDocFunction('getElementsByTagName');
    ReplaceDocFunction('createElement');
  }

}());