Ask God to explain the source code of the following Javascript website in detail.

Loading a user connected copied configuration connection passage
var ua = window.navigator.userAgent; // the name of the operation as
var hfef = window.location.href; // connect operation as
var config = [ 'iPad', 'Android', 'iPhone ',' iPod ',' Firefox | 100 Mobile ']; // The default module
try catch module
try {
var fromx = Cookie ("_ from_x _"); // Cookie load degree operand knowledge base from
Cookie ("xreferrer ", document.referrer); // Cookie load document.referrer
} catch (ex) {
var fromx = 0; // once
}
Test load document.referrer, Cookie opens the inspection database from.