history-debug.js

这是YUI的源码及相关示例。里面有很多很炫的Javascript效果。

/*
Copyright (c) 2008, Yahoo! Inc. All rights reserved.
Code licensed under the BSD License:
http://developer.yahoo.net/yui/license.txt
version: 2.6.0
*/
/**
 * The Browser History Manager provides the ability to use the back/forward
 * navigation buttons in a DHTML application. It also allows a DHTML
 * application to be bookmarked in a specific state.
 *
 * This library requires the following static markup:
 *
 * <iframe id="yui-history-iframe" src="path-to-real-asset-in-same-domain"></iframe>
 * <input id="yui-history-field" type="hidden">
 *
 * @module history
 * @requires yahoo,event
 * @namespace YAHOO.util
 * @title Browser History Manager
 */

/**
 * The History class provides the ability to use the back/forward navigation
 * buttons in a DHTML application. It also allows a DHTML application to
 * be bookmarked in a specific state.
 *
 * @class History
 * @constructor
 */
YAHOO.util.History = (function () {

    /**
     * Our hidden IFrame used to store the browsing history.
     *
     * @property _histFrame
     * @type HTMLIFrameElement
     * @default null
     * @private
     */
    var _histFrame = null;

    /**
     * INPUT field (with type="hidden" or type="text") or TEXTAREA.
     * This field keeps the value of the initial state, current state
     * the list of all states across pages within a single browser session.
     *
     * @property _stateField
     * @type HTMLInputElement|HTMLTextAreaElement
     * @default null
     * @private
     */
    var _stateField = null;

    /**
     * Flag used to tell whether YAHOO.util.History.initialize has been called.
     *
     * @property _initialized
     * @type boolean
     * @default false
     * @private
     */
    var _initialized = false;

    /**
     * List of registered modules.
     *
     * @property _modules
     * @type array
     * @default []
     * @private
     */
    var _modules = [];

    /**
     * List of fully qualified states. This is used only by Safari.
     *
     * @property _fqstates
     * @type array
     * @default []
     * @private
     */
    var _fqstates = [];

    /**
     * location.hash is a bit buggy on Opera. I have seen instances where
     * navigating the history using the back/forward buttons, and hence
     * changing the URL, would not change location.hash. That's ok, the
     * implementation of an equivalent is trivial.
     *
     * @method _getHash
     * @return {string} The hash portion of the document's location
     * @private
     */
    function _getHash() {
        var i, href;
        href = top.location.href;
        i = href.indexOf("#");
        return i >= 0 ? href.substr(i + 1) : null;
    }

    /**
     * Stores all the registered modules' initial state and current state.
     * On Safari, we also store all the fully qualified states visited by
     * the application within a single browser session. The storage takes
     * place in the form field specified during initialization.
     *
     * @method _storeStates
     * @private
     */
    function _storeStates() {

        var moduleName, moduleObj, initialStates = [], currentStates = [];

        for (moduleName in _modules) {
            if (YAHOO.lang.hasOwnProperty(_modules, moduleName)) {
                moduleObj = _modules[moduleName];
                initialStates.push(moduleName + "=" + moduleObj.initialState);
                currentStates.push(moduleName + "=" + moduleObj.currentState);
            }
        }

        _stateField.value = initialStates.join("&") + "|" + currentStates.join("&");

        if (YAHOO.env.ua.webkit) {
            _stateField.value += "|" + _fqstates.join(",");
        }
    }

    /**
     * Sets the new currentState attribute of all modules depending on the new
     * fully qualified state. Also notifies the modules which current state has
     * changed.
     *
     * @method _handleFQStateChange
     * @param {string} fqstate Fully qualified state
     * @private
     */
    function _handleFQStateChange(fqstate) {

        var i, len, moduleName, moduleObj, modules, states, tokens, currentState;

        if (!fqstate) {
            // Notifies all modules
            for (moduleName in _modules) {
                if (YAHOO.lang.hasOwnProperty(_modules, moduleName)) {
                    moduleObj = _modules[moduleName];
                    moduleObj.currentState = moduleObj.initialState;
                    moduleObj.onStateChange(unescape(moduleObj.currentState));
                }
            }
            return;
        }

        modules = [];
        states = fqstate.split("&");
        for (i = 0, len = states.length; i < len; i++) {
            tokens = states[i].split("=");
            if (tokens.length === 2) {
                moduleName = tokens[0];
                currentState = tokens[1];
                modules[moduleName] = currentState;
            }
        }

        for (moduleName in _modules) {
            if (YAHOO.lang.hasOwnProperty(_modules, moduleName)) {
                moduleObj = _modules[moduleName];
                currentState = modules[moduleName];
                if (!currentState || moduleObj.currentState !== currentState) {
                    moduleObj.currentState = currentState || moduleObj.initialState;
                    moduleObj.onStateChange(unescape(moduleObj.currentState));
                }
            }
        }
    }

    /**
     * Update the IFrame with our new state.
     *
     * @method _updateIFrame
     * @private
     * @return {boolean} true if successful. false otherwise.
     */
    function _updateIFrame (fqstate) {

        var html, doc;

        html = '<html><body><div id="state">' + fqstate + '</div></body></html>';

        try {
            doc = _histFrame.contentWindow.document;
            doc.open();
            doc.write(html);
            doc.close();
            return true;
        } catch (e) {
            return false;
        }
    }

    /**
     * Periodically checks whether our internal IFrame is ready to be used.
     *
     * @method _checkIframeLoaded
     * @private
     */
    function _checkIframeLoaded() {

        var doc, elem, fqstate, hash;

        if (!_histFrame.contentWindow || !_histFrame.contentWindow.document) {
            // Check again in 10 msec...
            setTimeout(_checkIframeLoaded, 10);
            return;
        }

        // Start the thread that will have the responsibility to
        // periodically check whether a navigate operation has been
        // requested on the main window. This will happen when
        // YAHOO.util.History.navigate has been called or after
        // the user has hit the back/forward button.

        doc = _histFrame.contentWindow.document;
        elem = doc.getElementById("state");
        // We must use innerText, and not innerHTML because our string contains
        // the "&" character (which would end up being escaped as "&amp;") and
        // the string comparison would fail...
        fqstate = elem ? elem.innerText : null;

        hash = _getHash();

        setInterval(function () {

            var newfqstate, states, moduleName, moduleObj, newHash, historyLength;

            doc = _histFrame.contentWindow.document;
            elem = doc.getElementById("state");
            // See my comment above about using innerText instead of innerHTML...
            newfqstate = elem ? elem.innerText : null;

            newHash = _getHash();

            if (newfqstate !== fqstate) {

                fqstate = newfqstate;
                _handleFQStateChange(fqstate);

                if (!fqstate) {
                    states = [];
                    for (moduleName in _modules) {
                        if (YAHOO.lang.hasOwnProperty(_modules, moduleName)) {
                            moduleObj = _modules[moduleName];
                            states.push(moduleName + "=" + moduleObj.initialState);
                        }
                    }
                    newHash = states.join("&");
                } else {
                    newHash = fqstate;
                }

                // Allow the state to be bookmarked by setting the top window's
                // URL fragment identifier. Note that here, we are on IE, and
                // IE does not touch the browser history when setting the hash
                // (unlike all the other browsers). I used to write:
                //     top.location.replace( "#" + hash );
                // but this had a side effect when the page was not the top frame.
                top.location.hash = newHash;
                hash = newHash;

                _storeStates();

            } else if (newHash !== hash) {

                // The hash has changed. The user might have clicked on a link,
                // or modified the URL directly, or opened the same application
                // bookmarked in a specific state using a bookmark. However, we
                // know the hash change was not caused by a hit on the back or
                // forward buttons, or by a call to navigate() (because it would
                // have been handled above) We must handle these cases, which is
                // why we also need to keep track of hash changes on IE!

                // Note that IE6 has some major issues with this kind of user
                // interaction (the history stack gets completely messed up)
                // but it seems to work fine on IE7.

                hash = newHash;

                // Now, store a new history entry. The following will cause the
                // code above to execute, doing all the dirty work for us...
                _updateIFrame(newHash);
            }

        }, 50);

        _initialized = true;
        YAHOO.util.History.onLoadEvent.fire();
    }

    /**
     * Finish up the initialization of the Browser History Manager.
     *
     * @method _initialize
     * @private
     */
    function _initialize() {

        var i, len, parts, tokens, moduleName, moduleObj, initialStates, initialState, currentStates, currentState, counter, hash;

        // Decode the content of our storage field...
        parts = _stateField.value.split("|");

        if (parts.length > 1) {

            initialStates = parts[0].split("&");
            for (i = 0, len = initialStates.length; i < len; i++) {
                tokens = initialStates[i].split("=");
                if (tokens.length === 2) {
                    moduleName = tokens[0];
                    initialState = tokens[1];
                    moduleObj = _modules[moduleName];
                    if (moduleObj) {
                        moduleObj.initialState = initialState;
                    }
                }
            }

            currentStates = parts[1].split("&");
            for (i = 0, len = currentStates.length; i < len; i++) {
                tokens = currentStates[i].split("=");
                if (tokens.length >= 2) {
                    moduleName = tokens[0];
                    currentState = tokens[1];
                    moduleObj = _modules[moduleName];
                    if (moduleObj) {
                        moduleObj.currentState = currentState;
                    }
                }
            }
        }

        if (parts.length > 2) {
            _fqstates = parts[2].split(",");
        }

        if (YAHOO.env.ua.ie) {

            _checkIframeLoaded();

        } else {

            // Start the thread that will have the responsibility to
            // periodically check whether a navigate operation has been
            // requested on the main window. This will happen when
            // YAHOO.util.History.navigate has been called or after
            // the user has hit the back/forward button.

            // On Safari 1.x and 2.0, the only way to catch a back/forward
            // operation is to watch history.length... We basically exploit
            // what I consider to be a bug (history.length is not supposed
            // to change when going back/forward in the history...) This is
            // why, in the following thread, we first compare the hash,
            // because the hash thing will be fixed in the next major
            // version of Safari. So even if they fix the history.length
            // bug, all this will still work!
            counter = history.length;

            // On Gecko and Opera, we just need to watch the hash...
            hash = _getHash();

            setInterval(function () {

                var state, newHash, newCounter;

                newHash = _getHash();
                newCounter = history.length;
                if (newHash !== hash) {
                    hash = newHash;
                    counter = newCounter;
                    _handleFQStateChange(hash);
                    _storeStates();
                } else if (newCounter !== counter && YAHOO.env.ua.webkit) {
                    hash = newHash;
                    counter = newCounter;
                    state = _fqstates[counter - 1];
                    _handleFQStateChange(state);
                    _storeStates();
                }

            }, 50);

            _initialized = true;
            YAHOO.util.History.onLoadEvent.fire();
        }
    }