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@feross
Created Jun 3, 2014
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/**
* Make a JSONP request. Server must support JSONP with callback name specified as a GET
* parameter with the name `callback`. Callback function will be called when data arrives.
* If request times out, callback is called with an Error object.
* @param {string} uri
* @param {Object} params Object of url params. Gets transformed into ?key1=value1&key2=value2
* @param {function} cb
*/
exports.jsonp = function (uri, params, cb) {
cb = once(cb)
// pick a globally-unique id
var id;
do {
id = '__jsonp_' + Math.round(Math.random() * 10000000);
} while (window[id] !== undefined);
uri += uri[uri.length - 1] === '/'
? ''
: '/';
uri += '?' + querystring.stringify(params) + '&callback=' + id;
var script = document.createElement('script');
script.src = uri;
var timeout = window.setTimeout(function () {
cb(new Error('jsonp request timed out'));
}, JSONP_TIMEOUT);
function cleanup () {
script.parentNode.removeChild(script); // cleanup script tag
delete window[id]; // cleanup global handler function
clearTimeout(timeout); // cleanup timeout
}
function cancel () {
if (window[id]) {
cleanup();
window[id] = function () {}; // noop
}
}
script.onerror = function () {
cleanup();
cb(new Error('jsonp error'));
};
window[id] = function (response) {
cleanup();
cb(null, response);
};
document.body.appendChild(script);
return cancel;
}
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