I took over managing a WordPress website build by someone else that we don't have contact with. The custom theme they are using appears to have been built on with a code generator (parser?) of some type. In order to reverse engineer this, I'm trying to figure out what kind of tool they used to create the site, as I can't easily update or make changes to said code.

Below is a section of a javascript file that is heavily used on the site. Any ideas of what they used to create code like this (and hopefully how I can edit it).

!(function (e) {
function t(t) {
    for (var s, n, o = t[0], l = t[1], u = t[2], p = 0, d = []; p < o.length; p++) (n = o[p]), Object.prototype.hasOwnProperty.call(r, n) && r[n] && d.push(r[n][0]), (r[n] = 0);
    for (s in l) Object.prototype.hasOwnProperty.call(l, s) && (e[s] = l[s]);
    for (c && c(t); d.length; ) d.shift()();
    return a.push.apply(a, u || []), i();
}
function i() {
    for (var e, t = 0; t < a.length; t++) {
        for (var i = a[t], s = !0, o = 1; o < i.length; o++) {
            var l = i[o];
            0 !== r[l] && (s = !1);
        }
        s && (a.splice(t--, 1), (e = n((n.s = i[0]))));
    }
    return e;
}
var s = {},
    r = { 0: 0 },
    a = [];
function n(t) {
    if (s[t]) return s[t].exports;
    var i = (s[t] = { i: t, l: !1, exports: {} });
    return e[t].call(i.exports, i, i.exports, n), (i.l = !0), i.exports;
}