source: Dev/branches/rest-dojo-ui/client/dojo/io/script.js @ 256

define(["../main"], function(dojo) {
        // module:
        //              dojo/io/script
        // summary:
        //              TODOC

        dojo.getObject("io", true, dojo);

/*=====
dojo.declare("dojo.io.script.__ioArgs", dojo.__IoArgs, {
        constructor: function(){
                //      summary:
                //              All the properties described in the dojo.__ioArgs type, apply to this
                //              type as well, EXCEPT "handleAs". It is not applicable to
                //              dojo.io.script.get() calls, since it is implied by the usage of
                //              "jsonp" (response will be a JSONP call returning JSON)
                //              or the response is pure JavaScript defined in
                //              the body of the script that was attached.
                //      callbackParamName: String
                //              Deprecated as of Dojo 1.4 in favor of "jsonp", but still supported for
                //              legacy code. See notes for jsonp property.
                //      jsonp: String
                //              The URL parameter name that indicates the JSONP callback string.
                //              For instance, when using Yahoo JSONP calls it is normally,
                //              jsonp: "callback". For AOL JSONP calls it is normally
                //              jsonp: "c".
                //      checkString: String
                //              A string of JavaScript that when evaluated like so:
                //              "typeof(" + checkString + ") != 'undefined'"
                //              being true means that the script fetched has been loaded.
                //              Do not use this if doing a JSONP type of call (use callbackParamName instead).
                //      frameDoc: Document
                //              The Document object for a child iframe. If this is passed in, the script
                //              will be attached to that document. This can be helpful in some comet long-polling
                //              scenarios with Firefox and Opera.
                this.callbackParamName = callbackParamName;
                this.jsonp = jsonp;
                this.checkString = checkString;
                this.frameDoc = frameDoc;
        }
});
=====*/

        var loadEvent = dojo.isIE ? "onreadystatechange" : "load",
                readyRegExp = /complete|loaded/;

        dojo.io.script = {
                get: function(/*dojo.io.script.__ioArgs*/args){
                        //      summary:
                        //              sends a get request using a dynamically created script tag.
                        var dfd = this._makeScriptDeferred(args);
                        var ioArgs = dfd.ioArgs;
                        dojo._ioAddQueryToUrl(ioArgs);

                        dojo._ioNotifyStart(dfd);

                        if(this._canAttach(ioArgs)){
                                var node = this.attach(ioArgs.id, ioArgs.url, args.frameDoc);

                                //If not a jsonp callback or a polling checkString case, bind
                                //to load event on the script tag.
                                if(!ioArgs.jsonp && !ioArgs.args.checkString){
                                        var handle = dojo.connect(node, loadEvent, function(evt){
                                                if(evt.type == "load" || readyRegExp.test(node.readyState)){
                                                        dojo.disconnect(handle);
                                                        ioArgs.scriptLoaded = evt;
                                                }
                                        });
                                }
                        }

                        dojo._ioWatch(dfd, this._validCheck, this._ioCheck, this._resHandle);
                        return dfd;
                },

                attach: function(/*String*/id, /*String*/url, /*Document?*/frameDocument){
                        //      summary:
                        //              creates a new <script> tag pointing to the specified URL and
                        //              adds it to the document.
                        //      description:
                        //              Attaches the script element to the DOM.  Use this method if you
                        //              just want to attach a script to the DOM and do not care when or
                        //              if it loads.
                        var doc = (frameDocument || dojo.doc);
                        var element = doc.createElement("script");
                        element.type = "text/javascript";
                        element.src = url;
                        element.id = id;
                        element.async = true;
                        element.charset = "utf-8";
                        return doc.getElementsByTagName("head")[0].appendChild(element);
                },

                remove: function(/*String*/id, /*Document?*/frameDocument){
                        //summary: removes the script element with the given id, from the given frameDocument.
                        //If no frameDocument is passed, the current document is used.
                        dojo.destroy(dojo.byId(id, frameDocument));

                        //Remove the jsonp callback on dojo.io.script, if it exists.
                        if(this["jsonp_" + id]){
                                delete this["jsonp_" + id];
                        }
                },

                _makeScriptDeferred: function(/*Object*/args){
                        //summary:
                        //              sets up a Deferred object for an IO request.
                        var dfd = dojo._ioSetArgs(args, this._deferredCancel, this._deferredOk, this._deferredError);

                        var ioArgs = dfd.ioArgs;
                        ioArgs.id = dojo._scopeName + "IoScript" + (this._counter++);
                        ioArgs.canDelete = false;

                        //Special setup for jsonp case
                        ioArgs.jsonp = args.callbackParamName || args.jsonp;
                        if(ioArgs.jsonp){
                                //Add the jsonp parameter.
                                ioArgs.query = ioArgs.query || "";
                                if(ioArgs.query.length > 0){
                                        ioArgs.query += "&";
                                }
                                ioArgs.query += ioArgs.jsonp
                                        + "="
                                        + (args.frameDoc ? "parent." : "")
                                        + dojo._scopeName + ".io.script.jsonp_" + ioArgs.id + "._jsonpCallback";

                                ioArgs.frameDoc = args.frameDoc;

                                //Setup the Deferred to have the jsonp callback.
                                ioArgs.canDelete = true;
                                dfd._jsonpCallback = this._jsonpCallback;
                                this["jsonp_" + ioArgs.id] = dfd;
                        }
                        return dfd; // dojo.Deferred
                },

                _deferredCancel: function(/*Deferred*/dfd){
                        //summary: canceller function for dojo._ioSetArgs call.

                        //DO NOT use "this" and expect it to be dojo.io.script.
                        dfd.canceled = true;
                        if(dfd.ioArgs.canDelete){
                                dojo.io.script._addDeadScript(dfd.ioArgs);
                        }
                },

                _deferredOk: function(/*Deferred*/dfd){
                        //summary: okHandler function for dojo._ioSetArgs call.

                        //DO NOT use "this" and expect it to be dojo.io.script.
                        var ioArgs = dfd.ioArgs;

                        //Add script to list of things that can be removed.
                        if(ioArgs.canDelete){
                                dojo.io.script._addDeadScript(ioArgs);
                        }

                        //Favor JSONP responses, script load events then lastly ioArgs.
                        //The ioArgs are goofy, but cannot return the dfd since that stops
                        //the callback chain in Deferred. The return value is not that important
                        //in that case, probably a checkString case.
                        return ioArgs.json || ioArgs.scriptLoaded || ioArgs;
                },

                _deferredError: function(/*Error*/error, /*Deferred*/dfd){
                        //summary: errHandler function for dojo._ioSetArgs call.

                        if(dfd.ioArgs.canDelete){
                                //DO NOT use "this" and expect it to be dojo.io.script.
                                if(error.dojoType == "timeout"){
                                        //For timeouts, remove the script element immediately to
                                        //avoid a response from it coming back later and causing trouble.
                                        dojo.io.script.remove(dfd.ioArgs.id, dfd.ioArgs.frameDoc);
                                }else{
                                        dojo.io.script._addDeadScript(dfd.ioArgs);
                                }
                        }
                        console.log("dojo.io.script error", error);
                        return error;
                },

                _deadScripts: [],
                _counter: 1,

                _addDeadScript: function(/*Object*/ioArgs){
                        //summary: sets up an entry in the deadScripts array.
                        dojo.io.script._deadScripts.push({id: ioArgs.id, frameDoc: ioArgs.frameDoc});
                        //Being extra paranoid about leaks:
                        ioArgs.frameDoc = null;
                },

                _validCheck: function(/*Deferred*/dfd){
                        //summary: inflight check function to see if dfd is still valid.

                        //Do script cleanup here. We wait for one inflight pass
                        //to make sure we don't get any weird things by trying to remove a script
                        //tag that is part of the call chain (IE 6 has been known to
                        //crash in that case).
                        var _self = dojo.io.script;
                        var deadScripts = _self._deadScripts;
                        if(deadScripts && deadScripts.length > 0){
                                for(var i = 0; i < deadScripts.length; i++){
                                        //Remove the script tag
                                        _self.remove(deadScripts[i].id, deadScripts[i].frameDoc);
                                        deadScripts[i].frameDoc = null;
                                }
                                dojo.io.script._deadScripts = [];
                        }

                        return true;
                },

                _ioCheck: function(/*Deferred*/dfd){
                        //summary: inflight check function to see if IO finished.
                        var ioArgs = dfd.ioArgs;
                        //Check for finished jsonp
                        if(ioArgs.json || (ioArgs.scriptLoaded && !ioArgs.args.checkString)){
                                return true;
                        }

                        //Check for finished "checkString" case.
                        var checkString = ioArgs.args.checkString;
                        return checkString && eval("typeof(" + checkString + ") != 'undefined'");


                },

                _resHandle: function(/*Deferred*/dfd){
                        //summary: inflight function to handle a completed response.
                        if(dojo.io.script._ioCheck(dfd)){
                                dfd.callback(dfd);
                        }else{
                                //This path should never happen since the only way we can get
                                //to _resHandle is if _ioCheck is true.
                                dfd.errback(new Error("inconceivable dojo.io.script._resHandle error"));
                        }
                },

                _canAttach: function(/*Object*/ioArgs){
                        //summary: A method that can be overridden by other modules
                        //to control when the script attachment occurs.
                        return true;
                },

                _jsonpCallback: function(/*JSON Object*/json){
                        //summary:
                        //              generic handler for jsonp callback. A pointer to this function
                        //              is used for all jsonp callbacks.  NOTE: the "this" in this
                        //              function will be the Deferred object that represents the script
                        //              request.
                        this.ioArgs.json = json;
                }
        };

        return dojo.io.script;
});