Based on http://tosbourn.com/2013/08/javascript/a-fix-for-window-location-origin-in-internet-explorer/

origin.js

var origin = function () {
    // IE10 Doesn't have window.location.origin :(
    if (!window.location.origin) {
        var port = window.location.port ? ':' + window.location.port : '';
        return window.location.protocol + "//" + window.location.hostname + port;
    } else {
        return window.location.origin;
    }
}