event.js

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                    return false;
                }

                var cacheItem = null;

                // The index is a hidden parameter; needed to remove it from
                // the method signature because it was tempting users to
                // try and take advantage of it, which is not possible.
                var index = arguments[3];
  
                if ("undefined" == typeof index) {
                    index = this._getCacheIndex(el, sType, fn);
                }

                if (index >= 0) {
                    cacheItem = listeners[index];
                }

                if (!el || !cacheItem) {
                    return false;
                }


                if (this.useLegacyEvent(el, sType)) {
                    var legacyIndex = this.getLegacyIndex(el, sType);
                    var llist = legacyHandlers[legacyIndex];
                    if (llist) {
                        for (i=0, len=llist.length; i<len; ++i) {
                            li = llist[i];
                            if (li && 
                                li[this.EL] == el && 
                                li[this.TYPE] == sType && 
                                li[this.FN] == fn) {
                                    llist.splice(i, 1);
                                    break;
                            }
                        }
                    }

                } else {
                    try {
                        this._simpleRemove(el, sType, cacheItem[this.WFN], false);
                    } catch(e) {
                        return false;
                    }
                }

                // removed the wrapped handler
                delete listeners[index][this.WFN];
                delete listeners[index][this.FN];
                listeners.splice(index, 1);

                return true;

            },

            /**
             * Returns the event's target element
             * @method getTarget
             * @param {Event} ev the event
             * @param {boolean} resolveTextNode when set to true the target's
             *                  parent will be returned if the target is a 
             *                  text node.  @deprecated, the text node is
             *                  now resolved automatically
             * @return {HTMLElement} the event's target
             * @static
             */
            getTarget: function(ev, resolveTextNode) {
                var t = ev.target || ev.srcElement;
                return this.resolveTextNode(t);
            },

            /**
             * In some cases, some browsers will return a text node inside
             * the actual element that was targeted.  This normalizes the
             * return value for getTarget and getRelatedTarget.
             * @method resolveTextNode
             * @param {HTMLElement} node node to resolve
             * @return {HTMLElement} the normized node
             * @static
             */
            resolveTextNode: function(node) {
                // if (node && node.nodeName && 
                        // "#TEXT" == node.nodeName.toUpperCase()) {
                if (node && 3 == node.nodeType) {
                    return node.parentNode;
                } else {
                    return node;
                }
            },

            /**
             * Returns the event's pageX
             * @method getPageX
             * @param {Event} ev the event
             * @return {int} the event's pageX
             * @static
             */
            getPageX: function(ev) {
                var x = ev.pageX;
                if (!x && 0 !== x) {
                    x = ev.clientX || 0;

                    if ( this.isIE ) {
                        x += this._getScrollLeft();
                    }
                }

                return x;
            },

            /**
             * Returns the event's pageY
             * @method getPageY
             * @param {Event} ev the event
             * @return {int} the event's pageY
             * @static
             */
            getPageY: function(ev) {
                var y = ev.pageY;
                if (!y && 0 !== y) {
                    y = ev.clientY || 0;

                    if ( this.isIE ) {
                        y += this._getScrollTop();
                    }
                }

                return y;
            },

            /**
             * Returns the pageX and pageY properties as an indexed array.
             * @method getXY
             * @param {Event} ev the event
             * @return {[x, y]} the pageX and pageY properties of the event
             * @static
             */
            getXY: function(ev) {
                return [this.getPageX(ev), this.getPageY(ev)];
            },

            /**
             * Returns the event's related target 
             * @method getRelatedTarget
             * @param {Event} ev the event
             * @return {HTMLElement} the event's relatedTarget
             * @static
             */
            getRelatedTarget: function(ev) {
                var t = ev.relatedTarget;
                if (!t) {
                    if (ev.type == "mouseout") {
                        t = ev.toElement;
                    } else if (ev.type == "mouseover") {
                        t = ev.fromElement;
                    }
                }

                return this.resolveTextNode(t);
            },

            /**
             * Returns the time of the event.  If the time is not included, the
             * event is modified using the current time.
             * @method getTime
             * @param {Event} ev the event
             * @return {Date} the time of the event
             * @static
             */
            getTime: function(ev) {
                if (!ev.time) {
                    var t = new Date().getTime();
                    try {
                        ev.time = t;
                    } catch(e) { 
                        return t;
                    }
                }

                return ev.time;
            },

            /**
             * Convenience method for stopPropagation + preventDefault
             * @method stopEvent
             * @param {Event} ev the event
             * @static
             */
            stopEvent: function(ev) {
                this.stopPropagation(ev);
                this.preventDefault(ev);
            },

            /**
             * Stops event propagation
             * @method stopPropagation
             * @param {Event} ev the event
             * @static
             */
            stopPropagation: function(ev) {
                if (ev.stopPropagation) {
                    ev.stopPropagation();
                } else {
                    ev.cancelBubble = true;
                }
            },

            /**
             * Prevents the default behavior of the event
             * @method preventDefault
             * @param {Event} ev the event
             * @static
             */
            preventDefault: function(ev) {
                if (ev.preventDefault) {
                    ev.preventDefault();
                } else {
                    ev.returnValue = false;
                }
            },
             
            /**
             * Finds the event in the window object, the caller's arguments, or
             * in the arguments of another method in the callstack.  This is
             * executed automatically for events registered through the event
             * manager, so the implementer should not normally need to execute
             * this function at all.
             * @method getEvent
             * @param {Event} e the event parameter from the handler
             * @return {Event} the event 
             * @static
             */
            getEvent: function(e) {
                var ev = e || window.event;

                if (!ev) {
                    var c = this.getEvent.caller;
                    while (c) {
                        ev = c.arguments[0];
                        if (ev && Event == ev.constructor) {
                            break;
                        }
                        c = c.caller;
                    }
                }

                return ev;
            },

            /**
             * Returns the charcode for an event
             * @method getCharCode
             * @param {Event} ev the event
             * @return {int} the event's charCode
             * @static
             */
            getCharCode: function(ev) {
                return ev.charCode || ev.keyCode || 0;
            },

            /**
             * Locating the saved event handler data by function ref
             *
             * @method _getCacheIndex
             * @static
             * @private
             */
            _getCacheIndex: function(el, sType, fn) {
                for (var i=0,len=listeners.length; i<len; ++i) {
                    var li = listeners[i];
                    if ( li                 && 
                         li[this.FN] == fn  && 
                         li[this.EL] == el  && 
                         li[this.TYPE] == sType ) {
                        return i;
                    }
                }

                return -1;
            },

            /**
             * Generates an unique ID for the element if it does not already 
             * have one.
             * @method generateId
             * @param el the element to create the id for
             * @return {string} the resulting id of the element
             * @static
             */
            generateId: function(el) {
                var id = el.id;

                if (!id) {
                    id = "yuievtautoid-" + counter;
                    ++counter;
                    el.id = id;
                }

                return id;
            },

            /**
             * We want to be able to use getElementsByTagName as a collection
             * to attach a group of events to.  Unfortunately, different 
             * browsers return different types of collections.  This function
             * tests to determine if the object is array-like.  It will also 
             * fail if the object is an array, but is empty.
             * @method _isValidCollection
             * @param o the object to test
             * @return {boolean} true if the object is array-like and populated
             * @static
             * @private
             */
            _isValidCollection: function(o) {
                // this.logger.debug(o.constructor.toString())
                // this.logger.debug(typeof o)

                return ( o                    && // o is something
                         o.length             && // o is indexed
                         typeof o != "string" && // o is not a string
                         !o.tagName           && // o is not an HTML element
                         !o.alert             && // o is not a window
                         typeof o[0] != "undefined" );

            },

            /**
             * @private
             * @property elCache
             * DOM element cache
             * @static
             */
            elCache: {},

            /**
             * We cache elements bound by id because when the unload event 
             * fires, we can no longer use document.getElementById
             * @method getEl
             * @static
             * @private
             */
            getEl: function(id) {
                return document.getElementById(id);
            },

            /**
             * Clears the element cache
             * @deprecated Elements are not cached any longer
             * @method clearCache
             * @static
             * @private
             */
            clearCache: function() { },

            /**
             * hook up any deferred listeners
             * @method _load
             * @static
             * @private
             */
            _load: function(e) {
                loadComplete = true;
                var EU = YAHOO.util.Event;
                // Remove the listener to assist with the IE memory issue, but not
                // for other browsers because FF 1.0x does not like it.
                if (this.isIE) {
                    EU._simpleRemove(window, "load", EU._load);
                }
            },

            /**
             * Polling function that runs before the onload event fires, 
             * attempting to attach to DOM Nodes as soon as they are 
             * available
             * @method _tryPreloadAttach
             * @static
             * @private
             */
            _tryPreloadAttach: function() {

                if (this.locked) {
                    return false;
                }

                this.locked = true;


                // keep trying until after the page is loaded.  We need to 
                // check the page load state prior to trying to bind the 
                // elements so that we can be certain all elements have been 
                // tested appropriately
                var tryAgain = !loadComplete;
                if (!tryAgain) {
                    tryAgain = (retryCount > 0);
                }

                // onAvailable
                var notAvail = [];
                for (var i=0,len=onAvailStack.length; i<len ; ++i) {
                    var item = onAvailStack[i];
                    if (item) {
                        var el = this.getEl(item.id);

                        if (el) {
                            // The element is available, but not necessarily ready
                            // @todo verify IE7 compatibility
                            // @todo should we test parentNode.nextSibling?
                            // @todo re-evaluate global content ready
                            if ( !item.checkReady || 
                                    loadComplete || 
                                    el.nextSibling ||
                                    (document && document.body) ) {

                                var scope = el;
                                if (item.override) {
                                    if (item.override === true) {
                                        scope = item.obj;
                                    } else {
                                        scope = item.override;
                                    }
                                }
                                item.fn.call(scope, item.obj);
                                //delete onAvailStack[i];
                                // null out instead of delete for Opera
                                onAvailStack[i] = null;
                            }
                        } else {
                            notAvail.push(item);
                        }
                    }
                }

                retryCount = (notAvail.length === 0) ? 0 : retryCount - 1;

                if (tryAgain) {
                    // we may need to strip the nulled out items here
                    this.startInterval();
                } else {
                    clearInterval(this._interval);
                    this._interval = null;
                }