/** * Dateiname : javascript/Handler.js * Autor : David Flanagan * Version : 1.0 */ var Handler = {}; // In DOM-compliant browsers, our functions are trivial wrappers around // addEventListener() and removeEventListener(). if (document.addEventListener) { Handler.add = function(element, eventType, handler) { element.addEventListener(eventType, handler, false); }; Handler.remove = function(element, eventType, handler) { element.removeEventListener(eventType, handler, false); }; } // In IE 5 and later, we use attachEvent() and detachEvent(), with a number of // hacks to make them compatible with addEventListener and removeEventListener. else if (document.attachEvent) { Handler.add = function(element, eventType, handler) { // Don't allow duplicate handler registrations // _find() is a private utility function defined below. if (Handler._find(element, eventType, handler) != -1) return; // To invoke the handler function as a method of the // element, we've got to define this nested function and register // it instead of the handler function itself. var wrappedHandler = function(e) { if (!e) e = window.event; // Create a synthetic event object with partial compatibility // with DOM events. var event = { _event: e, // In case we really want the IE event object type: e.type, // Event type target: e.srcElement, // Where the event happened currentTarget: element, // Where we're handling it relatedTarget: e.fromElement?e.fromElement:e.toElement, eventPhase: (e.srcElement==element)?2:3, // Mouse coordinates clientX: e.clientX, clientY: e.clientY, screenX: e.screenX, screenY: e.screenY, // Key state altKey: e.altKey, ctrlKey: e.ctrlKey, shiftKey: e.shiftKey, charCode: e.keyCode, // Event management functions stopPropagation: function() {this._event.cancelBubble = true;}, preventDefault: function() {this._event.returnValue = false;} } // Invoke the handler function as a method of the element, passing // the synthetic event object as its single argument. // Use Function.call() if defined; otherwise do a hack if (Function.prototype.call) handler.call(element, event); else { // If we don't have Function.call, fake it like this element._currentHandler = handler; element._currentHandler(event); element._currentHandler = null; } }; // Now register that nested function as our event handler. element.attachEvent("on" + eventType, wrappedHandler); // Now we must do some record keeping to associate the user-supplied // handler function and the nested function that invokes it. // We have to do this so that we can deregister the handler with the // remove() method and also deregister it automatically on page unload. // Store all info about this handler into an object var h = { element: element, eventType: eventType, handler: handler, wrappedHandler: wrappedHandler }; // Figure out what document this handler is part of. // If the element has no "document" property, it is not // a window or a document element, so it must be the document // object itself. var d = element.document || element; // Now get the window associated with that document var w = d.parentWindow; // We have to associate this handler with the window, // so we can remove it when the window is unloaded var id = Handler._uid(); // Generate a unique property name if (!w._allHandlers) w._allHandlers = {}; // Create object if needed w._allHandlers[id] = h; // Store the handler info in this object // And associate the id of the handler info with this element as well if (!element._handlers) element._handlers = []; element._handlers.push(id); // If there is not an onunload handler associated with the window, // register one now. if (!w._onunloadHandlerRegistered) { w._onunloadHandlerRegistered = true; w.attachEvent("onunload", Handler._removeAllHandlers); } }; Handler.remove = function(element, eventType, handler) { // Find this handler in the element._handlers[] array. var i = Handler._find(element, eventType, handler); if (i == -1) return; // If the handler was not registered, do nothing // Get the window of this element var d = element.document || element; var w = d.parentWindow; // Look up the unique id of this handler var handlerId = element._handlers[i]; // And use that to look up the handler info var h = w._allHandlers[handlerId]; // Using that info, we can detach the handler from the element element.detachEvent("on" + eventType, h.wrappedHandler); // Remove one element from the element._handlers array element._handlers.splice(i, 1); // And delete the handler info from the per-window _allHandlers object delete w._allHandlers[handlerId]; }; // A utility function to find a handler in the element._handlers array // Returns an array index or -1 if no matching handler is found Handler._find = function(element, eventType, handler) { var handlers = element._handlers; if (!handlers) return -1; // if no handlers registered, nothing found // Get the window of this element var d = element.document || element; var w = d.parentWindow; // Loop through the handlers associated with this element, looking // for one with the right type and function. // We loop backward because the most recently registered handler // is most likely to be the first removed one. for(var i = handlers.length-1; i >= 0; i--) { var handlerId = handlers[i]; // get handler id var h = w._allHandlers[handlerId]; // get handler info // If handler info matches type and handler function, we found it. if (h.eventType == eventType && h.handler == handler) return i; } return -1; // No match found }; Handler._removeAllHandlers = function() { // This function is registered as the onunload handler with // attachEvent. This means that the this keyword refers to the // window in which the event occurred. var w = this; // Iterate through all registered handlers for(id in w._allHandlers) { // Get handler info for this handler id var h = w._allHandlers[id]; // Use the info to detach the handler h.element.detachEvent("on" + h.eventType, h.wrappedHandler); // Delete the handler info from the window delete w._allHandlers[id]; } } // Private utility to generate unique handler ids Handler._counter = 0; Handler._uid = function() { return "h" + Handler._counter++; }; }