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loadJsonp.js
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loadJsonp.js
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define([
'../ThirdParty/Uri',
'../ThirdParty/when',
'./combine',
'./defaultValue',
'./defined',
'./DeveloperError',
'./objectToQuery',
'./queryToObject',
'./Request',
'./RequestScheduler'
], function(
Uri,
when,
combine,
defaultValue,
defined,
DeveloperError,
objectToQuery,
queryToObject,
Request,
RequestScheduler) {
'use strict';
/**
* Requests a resource using JSONP.
*
* @exports loadJsonp
*
* @param {String} url The URL to request.
* @param {Object} [options] Object with the following properties:
* @param {Object} [options.parameters] Any extra query parameters to append to the URL.
* @param {String} [options.callbackParameterName='callback'] The callback parameter name that the server expects.
* @param {Proxy} [options.proxy] A proxy to use for the request. This object is expected to have a getURL function which returns the proxied URL, if needed.
* @param {Request} [request] The request object. Intended for internal use only.
* @returns {Promise.<Object>|undefined} a promise that will resolve to the requested data when loaded. Returns undefined if <code>request.throttle</code> is true and the request does not have high enough priority.
*
*
* @example
* // load a data asynchronously
* Cesium.loadJsonp('some/webservice').then(function(data) {
* // use the loaded data
* }).otherwise(function(error) {
* // an error occurred
* });
*
* @see {@link http://wiki.commonjs.org/wiki/Promises/A|CommonJS Promises/A}
*/
function loadJsonp(url, options, request) {
//>>includeStart('debug', pragmas.debug);
if (!defined(url)) {
throw new DeveloperError('url is required.');
}
//>>includeEnd('debug');
options = defaultValue(options, defaultValue.EMPTY_OBJECT);
//generate a unique function name
var functionName;
do {
functionName = 'loadJsonp' + Math.random().toString().substring(2, 8);
} while (defined(window[functionName]));
var uri = new Uri(url);
var queryOptions = queryToObject(defaultValue(uri.query, ''));
if (defined(options.parameters)) {
queryOptions = combine(options.parameters, queryOptions);
}
var callbackParameterName = defaultValue(options.callbackParameterName, 'callback');
queryOptions[callbackParameterName] = functionName;
uri.query = objectToQuery(queryOptions);
url = uri.toString();
var proxy = options.proxy;
if (defined(proxy)) {
url = proxy.getURL(url);
}
request = defined(request) ? request : new Request();
request.url = url;
request.requestFunction = function() {
var deferred = when.defer();
//assign a function with that name in the global scope
window[functionName] = function(data) {
deferred.resolve(data);
try {
delete window[functionName];
} catch (e) {
window[functionName] = undefined;
}
};
loadJsonp.loadAndExecuteScript(url, functionName, deferred);
return deferred.promise;
};
return RequestScheduler.request(request);
}
// This is broken out into a separate function so that it can be mocked for testing purposes.
loadJsonp.loadAndExecuteScript = function(url, functionName, deferred) {
var script = document.createElement('script');
script.async = true;
script.src = url;
var head = document.getElementsByTagName('head')[0];
script.onload = function() {
script.onload = undefined;
head.removeChild(script);
};
script.onerror = function(e) {
deferred.reject(e);
};
head.appendChild(script);
};
loadJsonp.defaultLoadAndExecuteScript = loadJsonp.loadAndExecuteScript;
return loadJsonp;
});