event.js

这是YUI的源码及相关示例。里面有很多很炫的Javascript效果。

            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
             * @param {HTMLElement} boundEl the element the listener is attached to
             * @return {Event} the event 
             * @static
             */
            getEvent: function(e, boundEl) {
                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) {
                var code = ev.keyCode || ev.charCode || 0;

                // webkit key normalization
                if (YAHOO.env.ua.webkit && (code in webkitKeymap)) {
                    code = webkitKeymap[code];
                }
                return code;
            },

            /**
             * Locating the saved event handler data by function ref
             *
             * @method _getCacheIndex
             * @static
             * @private
             */
            _getCacheIndex: function(el, sType, fn) {
                for (var i=0, l=listeners.length; i<l; i=i+1) {
                    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) {
                try {
                    return ( o                     && // o is something
                             typeof o !== "string" && // o is not a string
                             o.length              && // o is indexed
                             !o.tagName            && // o is not an HTML element
                             !o.alert              && // o is not a window
                             typeof o[0] !== "undefined" );
                } catch(ex) {
                    return false;
                }

            },

            /**
             * @private
             * @property elCache
             * DOM element cache
             * @static
             * @deprecated Elements are not cached due to issues that arise when
             * elements are removed and re-added
             */
            elCache: {},

            /**
             * We cache elements bound by id because when the unload event 
             * fires, we can no longer use document.getElementById
             * @method getEl
             * @static
             * @private
             * @deprecated Elements are not cached any longer
             */
            getEl: function(id) {
                return (typeof id === "string") ? document.getElementById(id) : id;
            },

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

            /**
             * Custom event the fires when the dom is initially usable
             * @event DOMReadyEvent
             */
            DOMReadyEvent: new YAHOO.util.CustomEvent("DOMReady", this),

            /**
             * hook up any deferred listeners
             * @method _load
             * @static
             * @private
             */
            _load: function(e) {

                if (!loadComplete) {
                    loadComplete = true;
                    var EU = YAHOO.util.Event;

                    // Just in case DOMReady did not go off for some reason
                    EU._ready();

                    // Available elements may not have been detected before the
                    // window load event fires. Try to find them now so that the
                    // the user is more likely to get the onAvailable notifications
                    // before the window load notification
                    EU._tryPreloadAttach();

                }
            },

            /**
             * Fires the DOMReady event listeners the first time the document is
             * usable.
             * @method _ready
             * @static
             * @private
             */
            _ready: function(e) {
                var EU = YAHOO.util.Event;
                if (!EU.DOMReady) {
                    EU.DOMReady=true;

                    // Fire the content ready custom event
                    EU.DOMReadyEvent.fire();

                    // Remove the DOMContentLoaded (FF/Opera)
                    EU._simpleRemove(document, "DOMContentLoaded", EU._ready);
                }
            },

            /**
             * 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 (onAvailStack.length === 0) {
                    retryCount = 0;
                    clearInterval(this._interval);
                    this._interval = null;
                    return;
                }

                if (this.locked) {
                    return;
                }

                if (this.isIE) {
                    // Hold off if DOMReady has not fired and check current
                    // readyState to protect against the IE operation aborted
                    // issue.
                    if (!this.DOMReady) {
                        this.startInterval();
                        return;
                    }
                }

                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 && onAvailStack.length > 0);
                }

                // onAvailable
                var notAvail = [];

                var executeItem = function (el, item) {
                    var scope = el;
                    if (item.override) {
                        if (item.override === true) {
                            scope = item.obj;
                        } else {
                            scope = item.override;
                        }
                    }
                    item.fn.call(scope, item.obj);
                };

                var i, len, item, el, ready=[];

                // onAvailable onContentReady
                for (i=0, len=onAvailStack.length; i<len; i=i+1) {
                    item = onAvailStack[i];
                    if (item) {
                        el = this.getEl(item.id);
                        if (el) {
                            if (item.checkReady) {
                                if (loadComplete || el.nextSibling || !tryAgain) {
                                    ready.push(item);
                                    onAvailStack[i] = null;
                                }
                            } else {
                                executeItem(el, item);
                                onAvailStack[i] = null;
                            }
                        } else {
                            notAvail.push(item);
                        }
                    }
                }
                
                // make sure onContentReady fires after onAvailable
                for (i=0, len=ready.length; i<len; i=i+1) {
                    item = ready[i];
                    executeItem(this.getEl(item.id), item);
                }


                retryCount--;

                if (tryAgain) {
                    for (i=onAvailStack.length-1; i>-1; i--) {
                        item = onAvailStack[i];
                        if (!item || !item.id) {
                            onAvailStack.splice(i, 1);
                        }
                    }

                    this.startInterval();
                } else {
                    clearInterval(this._interval);
                    this._interval = null;
                }

                this.locked = false;

            },

            /**
             * Removes all listeners attached to the given element via addListener.
             * Optionally, the node's children can also be purged.
             * Optionally, you can specify a specific type of event to remove.
             * @method purgeElement
             * @param {HTMLElement} el the element to purge
             * @param {boolean} recurse recursively purge this element's children
             * as well.  Use with caution.
             * @param {string} sType optional type of listener to purge. If
             * left out, all listeners will be removed
             * @static
             */
            purgeElement: function(el, recurse, sType) {
                var oEl = (YAHOO.lang.isString(el)) ? this.getEl(el) : el;
                var elListeners = this.getListeners(oEl, sType), i, len;
                if (elListeners) {
                    for (i=elListeners.length-1; i>-1; i--) {
                        var l = elListeners[i];
                        this._removeListener(oEl, l.type, l.fn, l.capture);
                    }
                }

                if (recurse && oEl && oEl.childNodes) {
                    for (i=0,len=oEl.childNodes.length; i<len ; ++i) {
                        this.purgeElement(oEl.childNodes[i], recurse, sType);
                    }
                }
            },

            /**
             * Returns all listeners attached to the given element via addListener.
             * Optionally, you can specify a specific type of event to return.
             * @method getListeners
             * @param el {HTMLElement|string} the element or element id to inspect 
             * @param sType {string} optional type of listener to return. If
             * left out, all listeners will be returned
             * @return {Object} the listener. Contains the following fields:
             * &nbsp;&nbsp;type:   (string)   the type of event
             * &nbsp;&nbsp;fn:     (function) the callback supplied to addListener
             * &nbsp;&nbsp;obj:    (object)   the custom object supplied to addListen