/* $Id: OnDemandLoader.js,v 1.2 2009/05/06 19:18:12 cburck Exp $ */ var OnDemandLoader = { defaultPrefix : "/jscript/", loadedScripts : new Array(), // keeps track of what scripts have already been loaded loadingScripts : new Array(), // keeps track of what scripts are loading OutstandingLoads : 0, eventsRegister : new Array(), // keeps track of registered call back functions eventTypes : { Loads_Complete : "Called when all outstanding loads finish and no more are queued." }, loadRequiredLibs : function (config) { var src; /* go through all the required libraries */ for (var key in config) { /* get the expected location of the library */ src = config[key].src; /* load the library */ OnDemandLoader.loadScript(src); } }, unloadScripts : function (scripts) { /* ensure we got an array here */ if (typeof(scripts) != typeof(new Array())) { scripts = new Array(scripts); } var scriptElements = document.getElementsByTagName("script"); var src; /* loop through all script tags on the page */ for (var i = 0; i < scriptElements.length; i++) { /* get the file of the script */ src = scriptElements[i].getAttribute("src"); /* check if the script tag is an external tag, or embedded script */ if (src != null) { /* script tag is an external tag, so it may need to be removed */ for (var j = 0; j < scripts.length; j++) { /* see if the specified script matches */ if (src == scripts[j]) { // console.log("Unloading " + src); /* drop the element from the DOM */ scriptElements[i].parentNode.removeChild(scriptElements[i]); /* tracking the changes */ OnDemandLoader.loadedScripts[src] = false; j = scripts.length; /* only need to find one match */ } } } } }, loadScriptAsync : function (scripts) { // loads the specified script into a script tag if the script is not already loaded // if the input object is not an array, make it into one if (typeof(script) != typeof(new Array())) { scripts = new Array(scripts); } for (var i = 0; i < scripts.length; i++) { /* spin off javascript 'thread' */ setTimeout("OnDemandLoader.loadScript('" + scripts[i] + "');", 0); } }, loadScript : function (scripts) { // if the input object is not an array, make it into one if (typeof(scripts) != typeof(new Array())) { scripts = new Array(scripts); } //console.log(scripts); //console.log(" Size of load: " + scripts.length); for (var i = 0; i < scripts.length; i++) { //console.log("Looking at scipt #" + i + " (" + scripts[i] + ")"); OnDemandLoader.loadScript_Internal(scripts[i]); } }, loadScript_Internal : function (script) { /* get full path to script */ script = OnDemandLoader.defaultPrefix + script; /* make sure it is not already loaded or in the process of loading */ if (OnDemandLoader.isScriptLoaded(script) === false && OnDemandLoader.isScriptLoading(script) === false) { //console.log("Loading: " + script); /* set the script as in the process of loading */ OnDemandLoader.setLoading(script); // get the head tag from the document var head= document.getElementsByTagName('head')[0]; // create a new script tag var scriptTag= document.createElement('script'); // set the script location scriptTag.src= script; // set the script type scriptTag.setAttribute("language", "JavaScript"); // Keep IE happy scriptTag.type= 'text/JavaScript'; // make sure IE and some other browsers get this notification scriptTag.onreadystatechange = function () { if (this.readyState == 'loaded') { //console.log("On ready state change: " + script); /* wait a minute in case the loaded script starts spinning off additional loads */ setTimeout('OnDemandLoader.SignalLoaded("' + script + '");', 100); return; } return; } // make sure every other browser gets the notice scriptTag.onload = function () { //console.log("onLoad " + script); /* wait a minute in case the loaded script starts spinning off additional loads */ setTimeout('OnDemandLoader.SignalLoaded("' + script + '");', 100); return; } // keep track of how many outstanding loads are pending OnDemandLoader.OutstandingLoads++; //console.log("Outstanding Loads: " + OnDemandLoader.OutstandingLoads); // append the tag into the dom inside the head tag head.appendChild(scriptTag); } }, SignalLoaded : function (script) { //console.log("SignalLoaded: " + script); /* script is loaded */ OnDemandLoader.setLoaded(script); if (OnDemandLoader.isScriptLoading(script) === true) { /* clear the loading value so no other event can signal loaded */ OnDemandLoader.resetLoading(script); //console.log("Script Ready: " + script + "@" + new Date()); /* keeps track of total number of loading scripts */ OnDemandLoader.OutstandingLoads--; //console.log("Remaining scripts: " + OnDemandLoader.OutstandingLoads); /* all outstanding loads have completed */ if (OnDemandLoader.OutstandingLoads < 1) { /* error checking */ if (OnDemandLoader.OutstandingLoads < 0) { //console.log("Outstanding Loads count was less than 0: " + OnDemandLoader.OutstandingLoads); OnDemandLoader.OutstandingLoads = 0; } //console.log("All outstanding loads complete @" + new Date()); OnDemandLoader.triggerEvent('Loads_Complete'); } } }, registerEventCallBack : function (eventName, parameters) { if (typeof OnDemandLoader.eventTypes[eventName] == 'undefined') { console.log("Warning: registering " + parameters['call'] + " for an event that is not valid: " + eventName); } if (typeof OnDemandLoader.eventsRegister[eventName] != typeof new Array()) { OnDemandLoader.eventsRegister[eventName] = new Array(); } OnDemandLoader.eventsRegister[eventName].push(parameters); }, triggerEvent : function (event) { /* make it a proper event */ if (typeof event == 'string') { event = { name : event }; } //console.log("Triggered event " + event.name); if (typeof OnDemandLoader.eventTypes[event['name']] == 'undefined') { console.log("Warning: triggered event is not valid: " + event['name']); } var eventCallBacks = OnDemandLoader.eventsRegister[event['name']]; /* this will be repopulated with registrations that specify notification for future event instances */ delete OnDemandLoader.eventsRegister[event['name']]; /* no call backs */ if (eventCallBacks == null || typeof eventCallBacks != typeof new Array()) { return; } /* loop through all the callbacks */ for (var id = 0; id < eventCallBacks.size(); id++) { if (typeof eventCallBacks[id]['call'] == 'string') { eventCallBacks[id]['call'] = eval(eventCallBacks[id]['call']); } // trigger call back eventCallBacks[id]['call'](event); // reregister only if call back requests more than once if (eventCallBacks[id]['once'] == null || eventCallBacks[id]['once'] != true) { /* re-register event */ OnDemandLoader.registerEventCallBack(event['name'], eventCallBacks[id]); } } return; }, isScriptLoading : function (script) { /* see if it is in our list of loading scripts */ if (typeof(OnDemandLoader.loadingScripts[script]) == "undefined" || OnDemandLoader.loadingScripts[script] == null) { /* if not in our list, assume the script is not loading, and cache that value */ OnDemandLoader.resetLoading(script); //console.log("isScriptLoading: " + script + " undefined false"); return false; } //console.log("isScriptLoading: " + script + " defined " + OnDemandLoader.loadingScripts[script]); /* return the cached loading status */ return OnDemandLoader.loadingScripts[script]; }, isScriptLoaded : function (script) { // determines if a script is already loaded /* see if it is a script we know about yet */ if (typeof(OnDemandLoader.loadedScripts[script]) == "undefined" || OnDemandLoader.loadedScripts[script] == null) { //console.log("isScriptLoaded: " + script + " undefined false"); return false; } //console.log("isScriptLoaded: " + script + " defined " + OnDemandLoader.loadedScripts[script]); return OnDemandLoader.loadedScripts[script]; }, setLoaded : function (script) { // sets a script as loaded //console.log("Set loaded: " + script); OnDemandLoader.loadedScripts[script] = true; }, setUnloaded : function (script) { //console.log("Set unloaded: " + script); OnDemandLoader.loadedScripts[script] = false; }, setLoading : function (script) { // sets a script as loaded //console.log("Set loading: " + script); OnDemandLoader.loadingScripts[script] = true; }, resetLoading : function (script) { //console.log("Reset loading: " + script); OnDemandLoader.loadingScripts[script] = false; }, checkExistingScripts : function () { // determines if a script is already loaded /* look at all loaded scripts to see if it was loaded without the use of OnDemandLoader. */ var elements = document.getElementsByTagName("script"); var src; for (var i = 0; i < elements.length; i++) { src = elements.item(i).getAttribute("src"); /* see if the src attribute is set */ if (src != null) { /* as long as we are looking at it, might as well track it as if we loaded it */ OnDemandLoader.setLoaded(src); } } }, VersionCheck : { lib: function(libName, requiredVersion) { var libRef = window[libName]; if((typeof(libRef) == 'undefined') || (OnDemandLoader.VersionCheck.convertVersionString(libRef.Version) <= OnDemandLoader.VersionCheck.convertVersionString(requiredVersion))) { //throw("Required: the " + libName + " JavaScript library >= " + requiredVersion); /* version is not OK */ return false; } /* version is OK */ return true; }, requiredLibs : function (config) { var success = true; var versionRequired; /* go through all the required libraries */ for (var key in config) { /* check the config for the specified required version */ versionRequired = config[key].version; /* check the version */ if (!OnDemandLoader.VersionCheck.lib(key, versionRequired)) { /* at least one lib could not be found or could not have version verified */ success = false; } } return success; }, convertVersionString : function (version) { /* get rid of any alpha numeric characters and periods */ var versionNumber = version.replace(/_.*|\./g, ''); /* make sure correct number of digits in version number */ var padding; for (var i = 0; i < (8-versionNumber.length); i++) { padding = padding + '0'; } /* pad with up to eight zeroes */ versionNumber = parseInt(versionNumber + padding); /* return that number baby */ return versionNumber; } } }; // If the JavascriptDirectory is set, redefine the default script directory in the loader. if (typeof(JavascriptDirectory) != "undefined") { OnDemandLoader.defaultPrefix = JavascriptDirectory; } OnDemandLoader.checkExistingScripts();