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Cross-browser addEvent and removeEvent.
Created: 2005.08.13 - Modified 2013.09.17

//+ Carlos R. L. Rodrigues
//@ http://jsfromhell.com/geral/event-listener [rev. #6]

addEvent = function(o, e, f, s){
    var r = o[r = "_" + (e = "on" + e)] = o[r] || (o[e] ? [[o[e], o]] : []), a, c, d;
    r[r.length] = [f, s || o], o[e] = function(e){
        try{
            (e = e || event).preventDefault || (e.preventDefault = function(){e.returnValue = false;});
            e.stopPropagation || (e.stopPropagation = function(){e.cancelBubble = true;});
            e.target || (e.target = e.srcElement || null);
            e.keyValue = e.key = (e.which + 1 || e.keyCode + 1) - 1 || 0;
        }catch(f){}
        for(d = 1, f = r.length; f; r[--f] && (a = r[f][0], o = r[f][1], a.call ? c = a.call(o, e) : (o._ = a, c = o._(e), o._ = null), d &= c !== false));
        return e = null, !!d;
    }
};

removeEvent = function(o, e, f, s){
    for(var i = (e = o["_on" + e] || []).length; i;)
        if(e[--i] && e[i][0] == f && (s || o) == e[i][1])
            return delete e[i];
    return false;
};

Clique em qualquer lugar.

<script type="text/javascript">
//<![CDATA[

var a = function(){
    alert("Fun??o A");
}
var b = function(){
    alert(this.name + this.message);
}
var c = function(){
    removeEvent(document, "click", a);
    removeEvent(document, "click", c);
    alert("Fun??o C removeu a fun??o A e C do onclick");
}
var params = {message: " com par?metros", name: "Fun??o B"};

addEvent(document, "click", b, params);
//removeEvent(document, "click", b, params);
addEvent(document, "click", c);
addEvent(document, "click", a);

//]]>
</script>

Functions

addEvent(object: Object, event: String, handler: Function(e: Event): Boolean, [scope: Object = object]): void

Adds an event listener to an object.

object

object that will receive the listener

event

event name without the "on" prefix (click, mouseover, ...)

handler

function that will be called when the event occur, the event object will be sent as argument to this function, and besides the normal properties, it will *always* have:

• target: object that generated the event
• keyValue: keeps the character key code on keyboard events
• stopPropagation: method to avoid the event propagation
• preventDefault: method to avoid the default action

the preventDefault method can be emulated by returning "false" in the function

scope

scope (who the "this" inside the callback will refer to) that will be used when the function get invoked, the default value is the object on the first argument

removeEvent(object: Object, event: String, handler: function(e: Event): Boolean, [scope: Object = object]): Boolean

Removes a previously added listener from the object and returns true in case of success.

object

object that received the listener

event

event name without the "on" prefix (click, mouseover, ...)

handler

same function that was assigned on the addEvent

scope

same scope that was assigned on the addEvent (if you provided a scope, it's necessary to send the same object as argument, otherwise the listener won't be removed), the default value is the object on the first argument

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