The jsonp loader assumes that the JSON can be loaded from a url to which a + * callback function name can be appended, e.g. "http://www.test.com/getsomejson.php?callback=" + * The loader then appends a nonce function name which the JSON should include. + * This works for services like Google Spreadsheets, etc., and accepts remote URLs.
+ * + * @example Usage in TimeMap.init(): + + datasets: [ + { + title: "JSONP Dataset", + type: "jsonp", + options: { + url: "http://www.test.com/getsomejson.php?callback=" + } + } + ] + * + * @constructor + * @param {Object} options All options for the loader:
+ * {Array} url URL of JSON service to load, callback name left off
+ * {Function} preloadFunction Function to call on data before loading
+ * {Function} transformFunction Function to call on individual items before loading
+ *
+ */
+TimeMap.loaders.jsonp = function(options) {
+ // get standard functions and document
+ TimeMap.loaders.mixin(this, options);
+
+ /**
+ * Function to call on data object before loading
+ * @name TimeMap.loaders.jsonp#preload
+ * @function
+ * @parameter {Object} data Data to preload
+ * @return {Array} data Array of item data
+ */
+
+ /**
+ * Function to call on a single item data object before loading
+ * @name TimeMap.loaders.jsonp#transform
+ * @function
+ * @parameter {Object} data Data to transform
+ * @return {Object} data Transformed data for one item
+ */
+
+ /**
+ * URL to load, with missing callback parameter
+ * @example "http://www.example.com/myjsonservice?callback="
+ * @type String
+ */
+ this.url = options.url;
+};
+
+/**
+ * JSONP load function.
+ *
+ * @param {TimeMapDataset} dataset Dataset to load data into
+ * @param {Function} callback Function to call once data is loaded
+ */
+TimeMap.loaders.jsonp.prototype.load = function(dataset, callback) {
+ var loader = this;
+ // get items
+ TimeMap.loaders.jsonp.read(this.url, function(result) {
+ // load
+ var items = loader.preload(result);
+ dataset.loadItems(items, loader.transform);
+ // callback
+ callback();
+ });
+};
+
+/**
+ * Static - for naming callback functions
+ * @type int
+ */
+TimeMap.loaders.jsonp.counter = 0;
+
+/**
+ * Static - reads JSON from a URL, assuming that the service is set up to apply
+ * a callback function specified in the URL parameters.
+ *
+ * @param {String} jsonUrl URL to load, missing the callback function name
+ * @param {function} f Callback function to apply to returned data
+ */
+TimeMap.loaders.jsonp.read = function(url, f) {
+ // Define a unique function name
+ var callbackName = "_" + TimeMap.loaders.jsonp.counter++;
+
+ TimeMap.loaders.jsonp[callbackName] = function(result) {
+ // Pass result to user function
+ f(result);
+ // Delete the callback function
+ delete TimeMap.loaders.jsonp[callbackName];
+ };
+
+ // Create a script tag, set its src attribute and add it to the document
+ // This triggers the HTTP request and submits the query
+ var script = document.createElement("script");
+ script.src = url + "TimeMap.loaders.jsonp." + callbackName;
+ document.body.appendChild(script);
+};
+
+/**
+ * Static - cancel all current JSONP requests
+ * (note that this doesn't cancel the load, just the callback)
+ */
+TimeMap.loaders.jsonp.cancelAll = function() {
+ var namespace = TimeMap.loaders.jsonp;
+ for (var i in namespace){
+ // XXX: this is too cludgy - callback functions need their own namespace
+ if (i.substr(0,1) == '_'){
+ namespace[i] = function(){
+ delete namespace[i];
+ };
+ }
+ }
+};
+
+/**
+ * @class
+ * JSON string loader factory - expects a plain JSON array.
+ *
+ * The json_string loader assumes an array of items in plain JSON, with no + * callback function - this will require a local URL.
+ *Note that this loader requires lib/json2.pack.js.
+ * + * @augments TimeMap.loaders.remote + * + * @requires lib/json2.pack.js + * + * @example Usage in TimeMap.init(): + + datasets: [ + { + title: "JSON String Dataset", + type: "json_string", + options: { + url: "mydata.json" // Must be a local URL + } + } + ] + * + * @param {Object} options All options for the loader:
+ * {Array} url URL of JSON service to load, callback name left off
+ * {Function} preloadFunction Function to call on data before loading
+ * {Function} transformFunction Function to call on individual items before loading
+ *
+ * @return {TimeMap.loaders.remote} Remote loader configured for JSON strings
+ */
+TimeMap.loaders.json_string = function(options) {
+ var loader = new TimeMap.loaders.remote(options);
+
+ /**
+ * Parse a JSON string into a JavaScript object, using the json2.js library.
+ * @name TimeMap.loaders.json_string#parse
+ * @param {String} json JSON string to parse
+ * @returns {Object} Parsed JavaScript object
+ */
+ loader.parse = JSON.parse;
+
+ return loader;
+};
+
+// Probably the default json loader should be json_string, not
+// jsonp. I may change this in the future, so I'd encourage you to use
+// the specific one you want.
+TimeMap.loaders.json = TimeMap.loaders.jsonp;