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const XMLHttpRequest = require("xmlhttprequest-ssl");
const XHR = require("./polling-xhr");
const JSONP = require("./polling-jsonp");
const websocket = require("./websocket");
exports.polling = polling;
exports.websocket = websocket;
/**
* Polling transport polymorphic constructor.
* Decides on xhr vs jsonp based on feature detection.
*
* @api private
*/
function polling(opts) {
let xhr;
let xd = false;
let xs = false;
const jsonp = false !== opts.jsonp;
if (typeof location !== "undefined") {
const isSSL = "https:" === location.protocol;
let port = location.port;
// some user agents have empty `location.port`
if (!port) {
port = isSSL ? 443 : 80;
}
xd = opts.hostname !== location.hostname || port !== opts.port;
xs = opts.secure !== isSSL;
}
opts.xdomain = xd;
opts.xscheme = xs;
xhr = new XMLHttpRequest(opts);
if ("open" in xhr && !opts.forceJSONP) {
return new XHR(opts);
} else {
if (!jsonp) throw new Error("JSONP disabled");
return new JSONP(opts);
}
}