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Copyright (c) 2008, Yahoo! Inc. All rights reserved.
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Code licensed under the BSD License:
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http://developer.yahoo.net/yui/license.txt
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* Provides a mechanism to fetch remote resources and
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* insert them into a document
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* Fetches and inserts one or more script or link nodes into the document
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* @namespace YAHOO.util
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* @class YAHOO.util.Get
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YAHOO.util.Get = function() {
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* hash of queues to manage multiple requests
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* queue index used to generate transaction ids
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* node index used to generate unique node ids
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* interal property used to prevent multiple simultaneous purge
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* Generates an HTML element, this is not appended to a document
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* @param type {string} the type of element
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* @param attr {string} the attributes
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* @param win {Window} optional window to create the element in
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* @return {HTMLElement} the generated node
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var _node = function(type, attr, win) {
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var w = win || window, d=w.document, n=d.createElement(type);
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if (attr[i] && YAHOO.lang.hasOwnProperty(attr, i)) {
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n.setAttribute(i, attr[i]);
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* Generates a link node
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* @param url {string} the url for the css file
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* @param win {Window} optional window to create the node in
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* @return {HTMLElement} the generated node
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var _linkNode = function(url, win, charset) {
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var c = charset || "utf-8";
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return _node("link", {
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"id": "yui__dyn_" + (nidx++),
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* Generates a script node
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* @method _scriptNode
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* @param url {string} the url for the script file
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* @param win {Window} optional window to create the node in
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* @return {HTMLElement} the generated node
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var _scriptNode = function(url, win, charset) {
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var c = charset || "utf-8";
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return _node("script", {
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"id": "yui__dyn_" + (nidx++),
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"type": "text/javascript",
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* Returns the data payload for callback functions
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* @method _returnData
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var _returnData = function(q, msg) {
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var _get = function(nId, tId) {
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n = (lang.isString(nId)) ? q.win.document.getElementById(nId) : nId;
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_fail(tId, "target node not found: " + nId);
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* The request failed, execute fail handler with whatever
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* was accomplished. There isn't a failure case at the
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* moment unless you count aborted transactions
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* @param id {string} the id of the request
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var _fail = function(id, msg) {
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// execute failure callback
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var sc=q.scope || q.win;
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q.onFailure.call(sc, _returnData(q, msg));
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* The request is complete, so executing the requester's callback
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* @param id {string} the id of the request
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var _finish = function(id) {
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var msg = "transaction " + id + " was aborted";
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// execute success callback
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var sc=q.scope || q.win;
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q.onSuccess.call(sc, _returnData(q));
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* @param id {string} the id of the request
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var _timeout = function(id) {
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var sc=q.context || q;
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q.onTimeout.call(sc, _returnData(q));
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* Loads the next item for a given request
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* @param id {string} the id of the request
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* @param loaded {string} the url that was just loaded, if any
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var _next = function(id, loaded) {
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// Y.log('cancel timer');
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var msg = "transaction " + id + " was aborted";
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// This is the first pass: make sure the url is an array
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q.url = (lang.isString(q.url)) ? [q.url] : q.url;
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q.varName = (lang.isString(q.varName)) ? [q.varName] : q.varName;
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var w=q.win, d=w.document, h=d.getElementsByTagName("head")[0], n;
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if (q.url.length === 0) {
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// Safari 2.x workaround - There is no way to know when
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// a script is ready in versions of Safari prior to 3.x.
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// Adding an extra node reduces the problem, but doesn't
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// eliminate it completely because the browser executes
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// them asynchronously.
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if (q.type === "script" && ua.webkit && ua.webkit < 420 &&
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!q.finalpass && !q.varName) {
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// Add another script node. This does not guarantee that the
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// scripts will execute in order, but it does appear to fix the
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// problem on fast connections more effectively than using an
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// arbitrary timeout. It is possible that the browser does
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// block subsequent script execution in this case for a limited
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var extra = _scriptNode(null, q.win, q.charset);
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extra.innerHTML='YAHOO.util.Get._finalize("' + id + '");';
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q.nodes.push(extra); h.appendChild(extra);
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// if the url is undefined, this is probably a trailing comma problem in IE
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// Y.log('create timer');
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q.timer = lang.later(q.timeout, q, _timeout, id);
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if (q.type === "script") {
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n = _scriptNode(url, w, q.charset);
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n = _linkNode(url, w, q.charset);
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// track this node's load progress
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_track(q.type, n, id, url, w, q.url.length);
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// add the node to the queue so we can return it to the user supplied callback
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// add it to the head or insert it before 'insertBefore'
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if (q.insertBefore) {
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var s = _get(q.insertBefore, id);
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s.parentNode.insertBefore(n, s);
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// FireFox does not support the onload event for link nodes, so there is
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// no way to make the css requests synchronous. This means that the css
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// rules in multiple files could be applied out of order in this browser
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// if a later request returns before an earlier one. Safari too.
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if ((ua.webkit || ua.gecko) && q.type === "css") {
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* Removes processed queues and corresponding nodes
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var _autoPurge = function() {
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for (var i in queues) {
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if (q.autopurge && q.finished) {
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* Removes the nodes for the specified queue
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var _purge = function(tId) {
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var n=q.nodes, l=n.length, d=q.win.document,
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h=d.getElementsByTagName("head")[0];
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if (q.insertBefore) {
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var s = _get(q.insertBefore, tId);
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for (var i=0; i<l; i=i+1) {
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* Saves the state for the request and begins loading
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* @param type {string} the type of node to insert
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* @param url {string} the url to load
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* @param opts the hash of options for this request
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var _queue = function(type, url, opts) {
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var id = "q" + (qidx++);
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if (qidx % YAHOO.util.Get.PURGE_THRESH === 0) {
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queues[id] = lang.merge(opts, {
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q.win = q.win || window;
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q.scope = q.scope || q.win;
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q.autopurge = ("autopurge" in q) ? q.autopurge :
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(type === "script") ? true : false;
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lang.later(0, q, _next, id);
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* Detects when a node has been loaded. In the case of
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* script nodes, this does not guarantee that contained
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* script is ready to use.
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* @param type {string} the type of node to track
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* @param n {HTMLElement} the node to track
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* @param id {string} the id of the request
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* @param url {string} the url that is being loaded
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* @param win {Window} the targeted window
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* @param qlength the number of remaining items in the queue,
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* @param trackfn {Function} function to execute when finished
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* the default is _next
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var _track = function(type, n, id, url, win, qlength, trackfn) {
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var f = trackfn || _next;
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// IE supports the readystatechange event for script and css nodes
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n.onreadystatechange = function() {
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var rs = this.readyState;
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if ("loaded" === rs || "complete" === rs) {
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n.onreadystatechange = null;
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// webkit prior to 3.x is problemmatic
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} else if (ua.webkit) {
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if (type === "script") {
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// Safari 3.x supports the load event for script nodes (DOM2)
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if (ua.webkit >= 420) {
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n.addEventListener("load", function() {
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// Nothing can be done with Safari < 3.x except to pause and hope
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// for the best, particularly after last script is inserted. The
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// scripts will always execute in the order they arrive, not
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// necessarily the order in which they were inserted. To support
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// script nodes with complete reliability in these browsers, script
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// nodes either need to invoke a function in the window once they
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// are loaded or the implementer needs to provide a well-known
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// property that the utility can poll for.
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// Poll for the existence of the named variable, if it
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var freq=YAHOO.util.Get.POLL_FREQ;
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q.maxattempts = YAHOO.util.Get.TIMEOUT/freq;
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q._cache = q.varName[0].split(".");
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q.timer = lang.later(freq, q, function(o) {
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var a=this._cache, l=a.length, w=this.win, i;
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for (i=0; i<l; i=i+1) {
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// if we have exausted our attempts, give up
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if (this.attempts++ > this.maxattempts) {
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var msg = "Over retry limit, giving up";
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lang.later(YAHOO.util.Get.POLL_FREQ, null, f, [id, url]);
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// FireFox and Opera support onload (but not DOM2 in FF) handlers for
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// script nodes. Opera, but not FF, supports the onload event for link
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n.onload = function() {
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* The default poll freqency in ms, when needed
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* @property POLL_FREQ
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* The number of request required before an automatic purge.
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* property PURGE_THRESH
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* The length time to poll for varName when loading a script in
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* Safari 2.x before the transaction fails.
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* Called by the the helper for detecting script load in Safari
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* @param id {string} the transaction id
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_finalize: function(id) {
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lang.later(0, null, _finish, id);
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* Abort a transaction
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* @param {string|object} either the tId or the object returned from
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var id = (lang.isString(o)) ? o : o.tId;
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* Fetches and inserts one or more script nodes into the head
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* of the current document or the document in a specified window.
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* @param url {string|string[]} the url or urls to the script(s)
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* @param opts {object} Options:
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* callback to execute when the script(s) are finished loading
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* The callback receives an object back with the following
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* <dd>the window the script(s) were inserted into</dd>
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* <dd>the data object passed in when the request was made</dd>
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* <dd>An array containing references to the nodes that were
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* <dd>A function that, when executed, will remove the nodes
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* that were inserted</dd>
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* callback to execute when the script load operation fails
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* The callback receives an object back with the following
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* <dd>the window the script(s) were inserted into</dd>
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* <dd>the data object passed in when the request was made</dd>
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* <dd>An array containing references to the nodes that were
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* inserted successfully</dd>
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* <dd>A function that, when executed, will remove any nodes
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* that were inserted</dd>
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* callback to execute when a timeout occurs.
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* The callback receives an object back with the following
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* <dd>the window the script(s) were inserted into</dd>
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* <dd>the data object passed in when the request was made</dd>
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* <dd>An array containing references to the nodes that were
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* <dd>A function that, when executed, will remove the nodes
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* that were inserted</dd>
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* <dd>the execution context for the callbacks</dd>
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* <dd>a window other than the one the utility occupies</dd>
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* setting to true will let the utilities cleanup routine purge
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* the script once loaded
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* data that is supplied to the callback when the script(s) are
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* variable that should be available when a script is finished
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* loading. Used to help Safari 2.x and below with script load
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* detection. The type of this property should match what was
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* passed into the url parameter: if loading a single url, a
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* string can be supplied. If loading multiple scripts, you
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* must supply an array that contains the variable name for
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* <dt>insertBefore</dt>
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* <dd>node or node id that will become the new node's nextSibling</dd>
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* <dd>Node charset, default utf-8</dd>
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* <dd>Number of milliseconds to wait before aborting and firing the timeout event</dd>
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* // assumes yahoo, dom, and event are already on the page
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* YAHOO.util.Get.script(
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* ["http://yui.yahooapis.com/2.3.1/build/dragdrop/dragdrop-min.js",
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* "http://yui.yahooapis.com/2.3.1/build/animation/animation-min.js"], {
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* onSuccess: function(o) {
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* new YAHOO.util.DDProxy("dd1"); // also new o.reference("dd1"); would work
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* this.log("won't cause error because YAHOO is the scope");
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* this.log(o.nodes.length === 2) // true
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* // o.purge(); // optionally remove the script nodes immediately
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* },
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* onFailure: function(o) {
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* },
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* data: "foo",
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* timeout: 10000, // 10 second timeout
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* scope: YAHOO,
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* // win: otherframe // target another window/frame
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* autopurge: true // allow the utility to choose when to remove the nodes
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* });
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* @return {tId: string} an object containing info about the transaction
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script: function(url, opts) { return _queue("script", url, opts); },
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* Fetches and inserts one or more css link nodes into the
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* head of the current document or the document in a specified
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* @param url {string} the url or urls to the css file(s)
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* @param opts Options:
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* callback to execute when the css file(s) are finished loading
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* The callback receives an object back with the following
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* <dd>the window the link nodes(s) were inserted into</dd>
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* <dd>the data object passed in when the request was made</dd>
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* <dd>An array containing references to the nodes that were
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* <dd>A function that, when executed, will remove the nodes
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* that were inserted</dd>
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* <dd>the execution context for the callbacks</dd>
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* <dd>a window other than the one the utility occupies</dd>
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* data that is supplied to the callbacks when the nodes(s) are
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* <dt>insertBefore</dt>
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* <dd>node or node id that will become the new node's nextSibling</dd>
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* <dd>Node charset, default utf-8</dd>
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* YAHOO.util.Get.css("http://yui.yahooapis.com/2.3.1/build/menu/assets/skins/sam/menu.css");
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* YAHOO.util.Get.css(["http://yui.yahooapis.com/2.3.1/build/menu/assets/skins/sam/menu.css",
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* @return {tId: string} an object containing info about the transaction
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css: function(url, opts) {
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return _queue("css", url, opts);
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YAHOO.register("get", YAHOO.util.Get, {version: "2.6.0", build: "1321"});