Martin Vseticka Martin Vseticka - 23 days ago 4
Javascript Question

Is it possible to remove all event handlers of a given element in javascript?

I would like to remove ALL handlers for a given event type. Let's say I've added twice "onclick event" to a button and now I would like to return back to the original state where no event handler was set to the button.

How can I do that?

P.S.: I've found removeEventListener (non-IE)/detachEvent (IE) methods but the functions want me to pass as a parameter the function that handles the event which seems to me quite clumsy because I would have to store the functions somewhere.

EDIT: http://ejohn.org/blog/flexible-javascript-events/ - I'm now using this code

Answer

http://www.quirksmode.org/js/events_advanced.html - "Which event handlers are registered?" - it seems it's not possible without DOM 3 level :-(

EDIT: I've come up with this code. It suits my needs. Maybe it will be helpful for someone else.

Javascript:

function DomLib() {


}


/**
* Based on: http://ejohn.org/blog/flexible-javascript-events/
* Function that register event and enables it to be removed without explicitly giving the function definition
*/
DomLib.prototype.regEventEx = function (el, eventName, funct) {

  if (el.attachEvent) {
    el['e'+eventName+funct] = funct;
    el[eventName+funct] = function(){el['e'+eventName+funct](window.event);}
    el.attachEvent( 'on'+eventName, el[eventName+funct] );
  } else {    
    el.addEventListener(eventName, funct, false);
  } 

  if(!el.eventHolder) el.eventHolder = [];
  el.eventHolder[el.eventHolder.length] = new Array(eventName, funct);  
}

DomLib.prototype.removeEvent = function (obj, type, fn) {
  if (obj.detachEvent) {
    obj.detachEvent( 'on'+type, obj[type+fn] );
    obj[type+fn] = null;
  } else {
    obj.removeEventListener( type, fn, false );
  }  
}


DomLib.prototype.hasEventEx = function (el, eventName, funct) {

  if (!el.eventHolder) {  
    return false;
  } else {
    for (var i = 0; i < el.eventHolder.length; i++) {
      if (el.eventHolder[i][0] == eventType && String(el.eventHolder[i][1]) == String(funct)) {
        return true;  
      }  
    }
  }
  return false;  
}

/** 
* @return - returns true if an event was removed
*/
DomLib.prototype.removeEventsByTypeEx = function (el, eventType) {

  if (el.eventHolder) {  

    var removed = 0;
    for (var i = 0; i < el.eventHolder.length; i++) {
      if (el.eventHolder[i][0] == eventType) {                
        this.removeEvent(el, eventType, el.eventHolder[i][1]);
        el.eventHolder.splice(i, 1);
        removed++;
        i--;
      }  
    }

    return (removed > 0) ? true : false;
  } else {
    return false; 
  }
}

Testing HTML page:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<meta http-equiv="Expires" content="Fri, Jan 01 1900 00:00:00 GMT">
<meta http-equiv="Pragma" content="no-cache">
<meta http-equiv="Cache-Control" content="no-cache">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta http-equiv="Lang" content="en">
<meta name="author" content="">
<meta http-equiv="Reply-to" content="@.com">
<meta name="generator" content="PhpED 5.8">
<meta name="description" content="">
<meta name="keywords" content="">
<meta name="creation-date" content="01/01/2009">
<meta name="revisit-after" content="15 days">
<title>DomLibTest</title>
<link rel="stylesheet" type="text/css" href="my.css">
<!-- FILL IN: Location of your jQuery library -->
<script type="text/javascript" src="jQuery/jQuery-current.js"></script>
<!-- FILL IN: Plugin for debugging ... http://www.ecitadel.net/blog/2009/12/08/developing-jquery-use-dump-instead-alert -->
<script type="text/javascript" src="jQuery/jQuery.dump.js"></script>
<script type="text/javascript" src="DomLib.js"></script>
</head>
<body>

  <div id="testElem-1"></div>
  <script type="text/javascript">
  <!--

    var domLib = new DomLib();

    function removeTest(el) {

      var funct = function() { alert("#1: How Are You?");};
      var funct2 = function() { alert("#2: How Are You?");};                  

      domLib.regEventEx(el, "click", funct);
      domLib.regEventEx(el, "mousemove", funct2);
      domLib.regEventEx(el, "mousemove", funct2);
      domLib.regEventEx(el, "mousemove", funct2);

      $.dump(el.eventHolder);      
      domLib.removeEventsByTypeEx(el, "mousemove");      
      $.dump(el.eventHolder);
    }

    removeTest(document.getElementById('testElem-1'));

  -->
  </script>
</body>
</html>