• Created: 20/06/2015
• Last updated: 20/06/2015

I have been working on a js replacement / polyfill for the native range input as I need a consistent cross browser interface for this, and to be able to use it in old ie.It works by generating an HTML facade, which can be easily styled in many browsers, and as the user interacts with it, events are programmatically fired on the actual input element.

One of the main problems to solve in this project was; how can you fire js events programmatically in ie and browsers, without forcing a dependency on any third party libraries ?

After quite a bit of reading, I put this together(slightly modified to make it more re - usable):

    /**
    * Manages custom events
    *
    * @class Event
    * @private
    */
    var Event = {
      /**
      * Lazily evaluates which create method needed
      * @param eventName
      * @param [eventType=HTMLEvents] - type of event
      */
      create: function(eventName, eventType) {
        var method;
        var self = this;

        eventType = eventType || 'HTMLEvents';

        if (document.createEvent) {
          method = function(eventName) {
            var event = document.createEvent(eventType);

            // dont bubble
            event.initEvent(eventName, false, true);

            return event;
          };
        } else {
          // ie < 9
          // BUGFIX: Infinite loop on keypress in ie8
          // will update when i fix this
          method = function(eventName, eventType) {
            var _event = document.createEventObject(
              window.event
            );

            _event.cancelBubble = true;
            _event.eventType = eventName;
            return _event;
          };
        }

        self.create = method;
        return method(eventName);
      },

      /**
      * Lazily evaluates which fire event method is needed
      * @param el
      * @param eventName
      */
      fire: function(el, eventName, eventType, code) {
        var method;
        var self = this;

        if(document.createEvent) {
          method = function(el, eventName, eventType, code) {
            var event = self.create(eventName, eventType);

            if(eventType === 'KeyboardEvent') {
              var get = { get: function() { return code } };
              var defineProperty = Object.defineProperty;

              defineProperty(event, 'which', get);
              defineProperty(event, 'keyCode', get);
            }

            el.dispatchEvent(event);
          };
        } else {
          // ie < 9
          method = function(el, eventName, eventType, code) {
            var onEventName = ['on', eventName].join('');

            // Event names recognised by old ie
            // (without the 'on').
            // any event not in this list must be
            // handled differently in ie < 9
            var ieEvents = [
              'load',
              'unload',
              'blur',
              'change',
              'focus',
              'reset',
              'select',
              'submit',
              'abort',
              'keydown',
              'keypress',
              'keyup',
              'click',
              'dblclick',
              'mousedown',
              'mousemove',
              'mouseout',
              'mouseover',
              'mouseup'
            ];

            // no indexOf in old ie
            var isIeEvent = function(event) {
              for(var i = 0, l = ieEvents.length; i < l; i++) {
                if(ieEvents[i] === event) {
                  return true;
                }
              }

              return false;
            };

            if(isIeEvent(eventName)) {
              // Existing ie < 9 event name
              var _event = self.create(eventName);

              _event.keyCode = code;

              el.fireEvent(onEventName, _event);
            } else if(el[onEventName]) {
              el[onEventName]();
            }
          };
        }

        self.fire = method;
        method(el, eventName);
      }
    };

Event.fire allows you to fire an event of any name on any element in ie >= 8, and modern browsers.How convenient:)

Non standard ie < 9 events(events not listed in ieEvents above) must be bound like so in order to work in ie <= 8.

    el.onstrangeevent = function() { ... };

I would handle this by adding a method above for adding event listeners to elements.

Usage example:

    <div id="target">Target</div>

    <script>
      var target = document.getElementById('target');

      target.addEventListener('click', function() {
        alert('target was clicked!');
      });

      Event.fire(target, 'click');
    </script>

Andhere it is working on codepen.