spudly.shuoink.com

Ok, so here is my version of the popular addEvent() javascript function.

usage:

event_listener.add( object, event_type, function );

Example:

function init() {
   alert("the page is fully loaded");
}
event_listener.add(window,"onload", init);

-OR -

event_listener.add(window, "onload", function init() {
   alert("the page is fully loaded");
});

Then you can also remove events as well. Remove them in the same manner you created them. Like this:

event_listener.remove( object, event_type, function );

Example:

function init() {
   alert("the page is fully loaded");
}
event_listener.remove(window,"onload", init);

-OR -

event_listener.remove(window, "onload", function init() {
   alert("the page is fully loaded");
});

Ok, so here’s the code:

var event_listener = {
   add: function(node, event_type, function_reference) {
      node = $(node);
      // if this is the first time an event has been added
      // to this node, setup the event handling system
      if(
         typeof node[event_type] != 'function' ||
         typeof node[event_type+'_num'] == 'undefined'
      ) {
         node[ event_type + '_num' ] = 0;
         if( typeof node[event_type] == "function" ) {
            node[event_type + 0] = node[event_type];
            node[event_type + '_num']++;
         }
         // setup the actual event listener (onclick, onmouseover, etc...)
         node[event_type] = function(e){
            e = (e) ? e : window.event;
            var return_value = true;
            for(var i = 0; i < node[event_type + '_num']; i++) {
               if( node[event_type + i](e) === false) {
                  return_value = false;
               }
            }
            return return_value;
         }
      }
      // prevent duplicates - return if the function is already there
      for(var i = 0; i < node[event_type + '_num']; i++) {
         if( node[event_type + i] == function_reference ) {
            return false;
         }
      }
      node[ event_type + node[ event_type + '_num' ] ] = function_reference;
      node[ event_type + '_num' ]++;
      return true;
   },
   remove: function(node, event_type, func) {
      node = $(node);

      // if the node is not setup for the event handling system, do nothing
      if(
         typeof node[event_type] != 'function' ||
         typeof node[event_type + '_num'] == 'undefined' ||
         node[event_type + '_num'] == 0
      ) {
         return false;
      }

      // loop through functions. once target function is found, remove it. shift
      // subsequent functions up one number (kindof like Array.splice(i,1); )
      var found = false;
      for( var i = 0; i < node[event_type + '_num']; i++ ){
         if( !found ) {
            found = node[event_type+i] == func ||
            node[event_type+i].toString == func.toString;
         }
         if( found && ( i + 1 ) < node[event_type + '_num'] ) {
            node[ event_type + i] = node[event_type + ( i + 1 )];
         }
      }

      if(found) {
         node[event_type + '_num']--;
         return true;
      }

   }
};

Inspired by and/or based on the following:
Aaron Moore’s addEvent()
Dustin Diaz’s addEvent()