event.js

一个使用yui-ext库

                           YAHOO.util.Event.on(el, sType, fn, obj, override);
                        });

                        return true;
                    }
                }

                // Element should be an html element or an array if we get 
                // here.
                if (!el) {
                    return false;
                }

                // we need to make sure we fire registered unload events 
                // prior to automatically unhooking them.  So we hang on to 
                // these instead of attaching them to the window and fire the
                // handles explicitly during our one unload event.
                if ("unload" == sType && obj !== this) {
                    unloadListeners[unloadListeners.length] =
                            [el, sType, fn, obj, override];
                    return true;
                }


                // if the user chooses to override the scope, we use the custom
                // object passed in, otherwise the executing scope will be the
                // HTML element that the event is registered on
                var scope = el;
                if (override) {
                    if (override === true) {
                        scope = obj;
                    } else {
                        scope = override;
                    }
                }

                // wrap the function so we can return the obj object when
                // the event fires;
                var wrappedFn = function(e) {
                        return fn.call(scope, YAHOO.util.Event.getEvent(e), 
                                obj);
                    };

                var li = [el, sType, fn, wrappedFn, scope];
                var index = listeners.length;
                // cache the listener so we can try to automatically unload
                listeners[index] = li;

                if (this.useLegacyEvent(el, sType)) {
                    var legacyIndex = this.getLegacyIndex(el, sType);

                    // Add a new dom0 wrapper if one is not detected for this
                    // element
                    if ( legacyIndex == -1 || 
                                el != legacyEvents[legacyIndex][0] ) {

                        legacyIndex = legacyEvents.length;
                        legacyMap[el.id + sType] = legacyIndex;

                        // cache the signature for the DOM0 event, and 
                        // include the existing handler for the event, if any
                        legacyEvents[legacyIndex] = 
                            [el, sType, el["on" + sType]];
                        legacyHandlers[legacyIndex] = [];

                        el["on" + sType] = 
                            function(e) {
                                YAHOO.util.Event.fireLegacyEvent(
                                    YAHOO.util.Event.getEvent(e), legacyIndex);
                            };
                    }

                    // add a reference to the wrapped listener to our custom
                    // stack of events
                    //legacyHandlers[legacyIndex].push(index);
                    legacyHandlers[legacyIndex].push(li);

                } else {
                    try {
                        this._simpleAdd(el, sType, wrappedFn, false);
                    } catch(ex) {
                        // handle an error trying to attach an event.  If it fails
                        // we need to clean up the cache
                        this.lastError = ex;
                        this.removeListener(el, sType, fn);
                        return false;
                    }
                }

                return true;
                
            },

            /**
             * When using legacy events, the handler is routed to this object
             * so we can fire our custom listener stack.
             * @method fireLegacyEvent
             * @static
             * @private
             */
            fireLegacyEvent: function(e, legacyIndex) {
                var ok=true,le,lh,li,scope,ret;
                
                lh = legacyHandlers[legacyIndex];
                for (var i=0,len=lh.length; i<len; ++i) {
                    li = lh[i];
                    if ( li && li[this.WFN] ) {
                        scope = li[this.ADJ_SCOPE];
                        ret = li[this.WFN].call(scope, e);
                        ok = (ok && ret);
                    }
                }

                // Fire the original handler if we replaced one.  We fire this
                // after the other events to keep stopPropagation/preventDefault
                // that happened in the DOM0 handler from touching our DOM2
                // substitute
                le = legacyEvents[legacyIndex];
                if (le && le[2]) {
                    le[2](e);
                }
                
                return ok;
            },

            /**
             * Returns the legacy event index that matches the supplied 
             * signature
             * @method getLegacyIndex
             * @static
             * @private
             */
            getLegacyIndex: function(el, sType) {
                var key = this.generateId(el) + sType;
                if (typeof legacyMap[key] == "undefined") { 
                    return -1;
                } else {
                    return legacyMap[key];
                }
            },

            /**
             * Logic that determines when we should automatically use legacy
             * events instead of DOM2 events.  Currently this is limited to old
             * Safari browsers with a broken preventDefault
             * @method useLegacyEvent
             * @static
             * @private
             */
            useLegacyEvent: function(el, sType) {
                if (this.webkit && ("click"==sType || "dblclick"==sType)) {
                    var v = parseInt(this.webkit, 10);
                    if (!isNaN(v) && v<418) {
                        return true;
                    }
                }
                return false;
            },
                    
            /**
             * Removes an event handler
             *
             * @method removeListener
             *
             * @param {Object} el the html element or the id of the element to 
             * assign the event to.
             * @param {String} sType the type of event to remove.
             * @param {Function} fn the method the event invokes.  If fn is
             * undefined, then all event handlers for the type of event are 
             * removed.
             * @return {boolean} true if the unbind was successful, false 
             * otherwise.
             * @static
             */
            removeListener: function(el, sType, fn) {
                var i, len;

                // The el argument can be a string
                if (typeof el == "string") {
                    el = this.getEl(el);
                // The el argument can be an array of elements or element ids.
                } else if ( this._isValidCollection(el)) {
                    var ok = true;
                    for (i=0,len=el.length; i<len; ++i) {
                        ok = ( this.removeListener(el[i], sType, fn) && ok );
                    }
                    return ok;
                }

                if (!fn || !fn.call) {
                    //return false;
                    return this.purgeElement(el, false, sType);
                }


                if ("unload" == sType) {

                    for (i=0, len=unloadListeners.length; i<len; i++) {
                        var li = unloadListeners[i];
                        if (li && 
                            li[0] == el && 
                            li[1] == sType && 
                            li[2] == fn) {
                                unloadListeners.splice(i, 1);
                                return true;
                        }
                    }

                    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(ex) {
                        this.lastError = ex;
                        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