fetch-jsonp.js
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(function (global, factory) {
if (typeof define === 'function' && define.amd) {
define(['exports', 'module'], factory);
} else if (typeof exports !== 'undefined' && typeof module !== 'undefined') {
factory(exports, module);
} else {
var mod = {
exports: {}
};
factory(mod.exports, mod);
global.fetchJsonp = mod.exports;
}
})(this, function (exports, module) {
'use strict';
var defaultOptions = {
timeout: 5000,
jsonpCallback: 'callback',
jsonpCallbackFunction: null
};
function generateCallbackFunction() {
return 'jsonp_' + Date.now() + '_' + Math.ceil(Math.random() * 100000);
}
// Known issue: Will throw 'Uncaught ReferenceError: callback_*** is not defined'
// error if request timeout
function clearFunction(functionName) {
// IE8 throws an exception when you try to delete a property on window
// http://stackoverflow.com/a/1824228/751089
try {
delete window[functionName];
} catch (e) {
window[functionName] = undefined;
}
}
function removeScript(scriptId) {
var script = document.getElementById(scriptId);
document.getElementsByTagName('head')[0].removeChild(script);
}
function fetchJsonp(_url) {
var options = arguments.length <= 1 || arguments[1] === undefined ? {} : arguments[1];
// to avoid param reassign
var url = _url;
var timeout = options.timeout || defaultOptions.timeout;
var jsonpCallback = options.jsonpCallback || defaultOptions.jsonpCallback;
var timeoutId = undefined;
return new Promise(function (resolve, reject) {
var callbackFunction = options.jsonpCallbackFunction || generateCallbackFunction();
var scriptId = jsonpCallback + '_' + callbackFunction;
window[callbackFunction] = function (response) {
resolve({
ok: true,
// keep consistent with fetch API
json: function json() {
return Promise.resolve(response);
}
});
if (timeoutId) clearTimeout(timeoutId);
removeScript(scriptId);
clearFunction(callbackFunction);
};
// Check if the user set their own params, and if not add a ? to start a list of params
url += url.indexOf('?') === -1 ? '?' : '&';
var jsonpScript = document.createElement('script');
jsonpScript.setAttribute('src', '' + url + jsonpCallback + '=' + callbackFunction);
jsonpScript.id = scriptId;
document.getElementsByTagName('head')[0].appendChild(jsonpScript);
timeoutId = setTimeout(function () {
reject(new Error('JSONP request to ' + url + ' timed out'));
clearFunction(callbackFunction);
removeScript(scriptId);
}, timeout);
});
}
// export as global function
/*
let local;
if (typeof global !== 'undefined') {
local = global;
} else if (typeof self !== 'undefined') {
local = self;
} else {
try {
local = Function('return this')();
} catch (e) {
throw new Error('polyfill failed because global object is unavailable in this environment');
}
}
local.fetchJsonp = fetchJsonp;
*/
module.exports = fetchJsonp;
});