JavaScript: EventTarget.addEventListener shim

EventTarget.addEventListener.js

// target.addEventListener shim, hat tip [mdn](http://mzl.la/18ELrGJ)
(function() {
  if (!Event.prototype.preventDefault) {
    Event.prototype.preventDefault=function() {
      this.returnValue=false;
    };
  }
  if (!Event.prototype.stopPropagation) {
    Event.prototype.stopPropagation=function() {
      this.cancelBubble=true;
    };
  }
  if (!Element.prototype.addEventListener) {
    var eventListeners=[];
    
    var addEventListener=function(type,listener /*, useCapture (will be ignored) */) {
      var self=this;
      var wrapper=function(e) {
        e.target=e.srcElement;
        e.currentTarget=self;
        if (listener.handleEvent) {
          listener.handleEvent(e);
        } else {
          listener.call(self,e);
        }
      };
      if (type=="DOMContentLoaded") {
        var wrapper2=function(e) {
          if (document.readyState=="complete") {
            wrapper(e);
          }
        };
        document.attachEvent("onreadystatechange",wrapper2);
        eventListeners.push({object:this,type:type,listener:listener,wrapper:wrapper2});
        
        if (document.readyState=="complete") {
          var e=new Event();
          e.srcElement=window;
          wrapper2(e);
        }
      } else {
        this.attachEvent("on"+type,wrapper);
        eventListeners.push({object:this,type:type,listener:listener,wrapper:wrapper});
      }
    };
    var removeEventListener=function(type,listener /*, useCapture (will be ignored) */) {
      var counter=0;
      while (counter<eventListeners.length) {
        var eventListener=eventListeners[counter];
        if (eventListener.object==this && eventListener.type==type && eventListener.listener==listener) {
          if (type=="DOMContentLoaded") {
            this.detachEvent("onreadystatechange",eventListener.wrapper);
          } else {
            this.detachEvent("on"+type,eventListener.wrapper);
          }
          break;
        }
        ++counter;
      }
    };
    Element.prototype.addEventListener=addEventListener;
    Element.prototype.removeEventListener=removeEventListener;
    if (HTMLDocument) {
      HTMLDocument.prototype.addEventListener=addEventListener;
      HTMLDocument.prototype.removeEventListener=removeEventListener;
    }
    if (Window) {
      Window.prototype.addEventListener=addEventListener;
      Window.prototype.removeEventListener=removeEventListener;
    }
  }
})();

EventTarget.addEventListener.min.js

// target.addEventListener shim, hat tip [mdn](http://mzl.la/18ELrGJ)
!function(){if(Event.prototype.preventDefault||(Event.prototype.preventDefault=function(){this.returnValue=!1}),Event.prototype.stopPropagation||(Event.prototype.stopPropagation=function(){this.cancelBubble=!0}),!Element.prototype.addEventListener){var a=[],b=function(b,c){var d=this,e=function(a){a.target=a.srcElement,a.currentTarget=d,c.handleEvent?c.handleEvent(a):c.call(d,a)};if("DOMContentLoaded"==b){var f=function(a){"complete"==document.readyState&&e(a)};if(document.attachEvent("onreadystatechange",f),a.push({object:this,type:b,listener:c,wrapper:f}),"complete"==document.readyState){var g=new Event;g.srcElement=window,f(g)}}else this.attachEvent("on"+b,e),a.push({object:this,type:b,listener:c,wrapper:e})},c=function(b,c){for(var d=0;d<a.length;){var e=a[d];if(e.object==this&&e.type==b&&e.listener==c){"DOMContentLoaded"==b?this.detachEvent("onreadystatechange",e.wrapper):this.detachEvent("on"+b,e.wrapper);break}++d}};Element.prototype.addEventListener=b,Element.prototype.removeEventListener=c,HTMLDocument&&(HTMLDocument.prototype.addEventListener=b,HTMLDocument.prototype.removeEventListener=c),Window&&(Window.prototype.addEventListener=b,Window.prototype.removeEventListener=c)}}();