Yahoo! UI Library > history > history.js (source view)
/**
* 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 "&") 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();
}
}
return {
/**
* Fired when the Browser History Manager is ready. If you subscribe to
* this event after the Browser History Manager has been initialized,
* it will not fire. Therefore, it is recommended to use the onReady
* method instead.
*
* @event onLoadEvent
* @see onReady
*/
onLoadEvent: new YAHOO.util.CustomEvent("onLoad"),
/**
* Executes the supplied callback when the Browser History Manager is
* ready. This will execute immediately if called after the Browser
* History Manager onLoad event has fired.
*
* @method onReady
* @param {function} fn what to execute when the Browser History Manager is ready.
* @param {object} obj an optional object to be passed back as a parameter to fn.
* @param {boolean|object} override If true, the obj passed in becomes fn's execution scope.
* @see onLoadEvent
*/
onReady: function (fn, obj, override) {
if (_initialized) {
setTimeout(function () {
var ctx = window;
if (override) {
if (override === true) {
ctx = obj;
} else {
ctx = override;
}
}
fn.call(ctx, "onLoad", [], obj);
}, 0);
} else {
YAHOO.util.History.onLoadEvent.subscribe(fn, obj, override);
}
},
/**
* Registers a new module.
*
* @method register
* @param {string} module Non-empty string uniquely identifying the
* module you wish to register.
* @param {string} initialState The initial state of the specified
* module corresponding to its earliest history entry.
* @param {function} onStateChange Callback called when the
* state of the specified module has changed.
* @param {object} obj An arbitrary object that will be passed as a
* parameter to the handler.
* @param {boolean} override If true, the obj passed in becomes the
* execution scope of the listener.
*/
register: function (module, initialState, onStateChange, obj, override) {
var scope, wrappedFn;
if (typeof module !== "string" || YAHOO.lang.trim(module) === "" ||
typeof initialState !== "string" ||
typeof onStateChange !== "function") {
throw new Error("Missing or invalid argument");
}
if (_modules[module]) {
// Here, we used to throw an exception. However, users have
// complained about this behavior, so we now just return.
return;
}
// Note: A module CANNOT be registered after calling
// YAHOO.util.History.initialize. Indeed, we set the initial state
// of each registered module in YAHOO.util.History.initialize.
// If you could register a module after initializing the Browser
// History Manager, you would not read the correct state using
// YAHOO.util.History.getCurrentState when coming back to the
// page using the back button.
if (_initialized) {
throw new Error("All modules must be registered before calling YAHOO.util.History.initialize");
}
// Make sure the strings passed in do not contain our separators "," and "|"
module = escape(module);
initialState = escape(initialState);
// If the user chooses to override the scope, we use the
// custom object passed in as the execution scope.
scope = null;
if (override === true) {
scope = obj;
} else {
scope = override;
}
wrappedFn = function (state) {
return onStateChange.call(scope, state, obj);
};
_modules[module] = {
name: module,
initialState: initialState,
currentState: initialState,
onStateChange: wrappedFn
};
},
/**
* Initializes the Browser History Manager. Call this method
* from a script block located right after the opening body tag.
*
* @method initialize
* @param {string|HTML Element} stateField <input type="hidden"> used
* to store application states. Must be in the static markup.
* @param {string|HTML Element} histFrame IFrame used to store
* the history (only required on Internet Explorer)
* @public
*/
initialize: function (stateField, histFrame) {
if (_initialized) {
// The browser history manager has already been initialized.
return;
}
if (YAHOO.env.ua.opera) {
// Opera cannot be supported because of several problems that
// have been reported to the Opera team, but never addressed:
// 1) Hash changes are not detected (started happening with
// recent versions of Opera)
// 2) The entire DOM gets cached, so when you come back to
// a page, the window's onload event does not get fired,
// which prevents us from initializing the browser history
// manager.
// As a consequence, the best thing we can do is to throw an
// exception. The application should catch it, and degrade
// gracefully. This is the sad state of history management.
YAHOO.log("Unsupported browser.", "error", this.toString());
}
if (typeof stateField === "string") {
stateField = document.getElementById(stateField);
}
if (!stateField ||
stateField.tagName.toUpperCase() !== "TEXTAREA" &&
(stateField.tagName.toUpperCase() !== "INPUT" ||
stateField.type !== "hidden" &&
stateField.type !== "text")) {
throw new Error("Missing or invalid argument");
}
_stateField = stateField;
if (YAHOO.env.ua.ie) {
if (typeof histFrame === "string") {
histFrame = document.getElementById(histFrame);
}
if (!histFrame || histFrame.tagName.toUpperCase() !== "IFRAME") {
throw new Error("Missing or invalid argument");
}
_histFrame = histFrame;
}
// Note that the event utility MUST be included inline in the page.
// If it gets loaded later (which you may want to do to improve the
// loading speed of your site), the onDOMReady event never fires,
// and the history library never gets fully initialized.
YAHOO.util.Event.onDOMReady(_initialize);
},
/**
* Call this method when you want to store a new entry in the browser's history.
*
* @method navigate
* @param {string} module Non-empty string representing your module.
* @param {string} state String representing the new state of the specified module.
* @return {boolean} Indicates whether the new state was successfully added to the history.
* @public
*/
navigate: function (module, state) {
var states;
if (typeof module !== "string" || typeof state !== "string") {
throw new Error("Missing or invalid argument");
}
states = {};
states[module] = state;
return YAHOO.util.History.multiNavigate(states);
},
/**
* Call this method when you want to store a new entry in the browser's history.
*
* @method multiNavigate
* @param {object} states Associative array of module-state pairs to set simultaneously.
* @return {boolean} Indicates whether the new state was successfully added to the history.
* @public
*/
multiNavigate: function (states) {
var currentStates, moduleName, moduleObj, currentState, fqstate;
if (typeof states !== "object") {
throw new Error("Missing or invalid argument");
}
if (!_initialized) {
throw new Error("The Browser History Manager is not initialized");
}
for (moduleName in states) {
if (!_modules[moduleName]) {
throw new Error("The following module has not been registered: " + moduleName);
}
}
// Generate our new full state string mod1=xxx&mod2=yyy
currentStates = [];
for (moduleName in _modules) {
if (YAHOO.lang.hasOwnProperty(_modules, moduleName)) {
moduleObj = _modules[moduleName];
if (YAHOO.lang.hasOwnProperty(states, moduleName)) {
currentState = states[unescape(moduleName)];
} else {
currentState = unescape(moduleObj.currentState);
}
// Make sure the strings passed in do not contain our separators "," and "|"
moduleName = escape(moduleName);
currentState = escape(currentState);
currentStates.push(moduleName + "=" + currentState);
}
}
fqstate = currentStates.join("&");
if (YAHOO.env.ua.ie) {
return _updateIFrame(fqstate);
} else {
// Known bug: On Safari 1.x and 2.0, if you have tab browsing
// enabled, Safari will show an endless loading icon in the
// tab. This has apparently been fixed in recent WebKit builds.
// One work around found by Dav Glass is to submit a form that
// points to the same document. This indeed works on Safari 1.x
// and 2.0 but creates bigger problems on WebKit. So for now,
// we'll consider this an acceptable bug, and hope that Apple
// comes out with their next version of Safari very soon.
top.location.hash = fqstate;
if (YAHOO.env.ua.webkit) {
// The following two lines are only useful for Safari 1.x
// and 2.0. Recent nightly builds of WebKit do not require
// that, but unfortunately, it is not easy to differentiate
// between the two. Once Safari 2.0 departs the A-grade
// list, we can remove the following two lines...
_fqstates[history.length] = fqstate;
_storeStates();
}
return true;
}
},
/**
* Returns the current state of the specified module.
*
* @method getCurrentState
* @param {string} module Non-empty string representing your module.
* @return {string} The current state of the specified module.
* @public
*/
getCurrentState: function (module) {
var moduleObj;
if (typeof module !== "string") {
throw new Error("Missing or invalid argument");
}
if (!_initialized) {
throw new Error("The Browser History Manager is not initialized");
}
moduleObj = _modules[module];
if (!moduleObj) {
throw new Error("No such registered module: " + module);
}
return unescape(moduleObj.currentState);
},
/**
* Returns the state of a module according to the URL fragment
* identifier. This method is useful to initialize your modules
* if your application was bookmarked from a particular state.
*
* @method getBookmarkedState
* @param {string} module Non-empty string representing your module.
* @return {string} The bookmarked state of the specified module.
* @public
*/
getBookmarkedState: function (module) {
var i, len, idx, hash, states, tokens, moduleName;
if (typeof module !== "string") {
throw new Error("Missing or invalid argument");
}
// Use location.href instead of location.hash which is already
// URL-decoded, which creates problems if the state value
// contained special characters...
idx = top.location.href.indexOf("#");
hash = idx >= 0 ? top.location.href.substr(idx + 1) : top.location.href;
states = hash.split("&");
for (i = 0, len = states.length; i < len; i++) {
tokens = states[i].split("=");
if (tokens.length === 2) {
moduleName = tokens[0];
if (moduleName === module) {
return unescape(tokens[1]);
}
}
}
return null;
},
/**
* Returns the value of the specified query string parameter.
* This method is not used internally by the Browser History Manager.
* However, it is provided here as a helper since many applications
* using the Browser History Manager will want to read the value of
* url parameters to initialize themselves.
*
* @method getQueryStringParameter
* @param {string} paramName Name of the parameter we want to look up.
* @param {string} queryString Optional URL to look at. If not specified,
* this method uses the URL in the address bar.
* @return {string} The value of the specified parameter, or null.
* @public
*/
getQueryStringParameter: function (paramName, url) {
var i, len, idx, queryString, params, tokens;
url = url || top.location.href;
idx = url.indexOf("?");
queryString = idx >= 0 ? url.substr(idx + 1) : url;
// Remove the hash if any
idx = queryString.lastIndexOf("#");
queryString = idx >= 0 ? queryString.substr(0, idx) : queryString;
params = queryString.split("&");
for (i = 0, len = params.length; i < len; i++) {
tokens = params[i].split("=");
if (tokens.length >= 2) {
if (tokens[0] === paramName) {
return unescape(tokens[1]);
}
}
}
return null;
}
};
})();