Inspecting a chrome plugin source after beautifying

I'm inspecting the source of a chrome plugin after running the compacted source through js-beautify. Each js file has some boilerplate followed by a list of enumerated functions. I'm trying to work out what tool would make code like this and why so I can try and work out the logic, and thus modify the plugin (I'm a suffering c++ person with minimal experience with js tools). Firstly, what is this boilerplate and where did it come from?

(function() {
    function b(d, e, g) {
        function a(j, i) {
            if (!e[j]) {
                if (!d[j]) {
                    var f = "function" == typeof require && require;
                    if (!i && f) return f(j, !0);
                    if (h) return h(j, !0);
                    var c = new Error("Cannot find module '" + j + "'");
                    throw c.code = "MODULE_NOT_FOUND", c
                }
                var k = e[j] = {
                    exports: {}
                };
                d[j][0].call(k.exports, function(b) {
                    var c = d[j][1][b];
                    return a(c || b)
                }, k, k.exports, b, d, e, g)
            }
            return e[j].exports
        }
        for (var h = "function" == typeof require && require, c = 0; c < g.length; c++) a(g[c]);
        return a
    }
    return b
})()({

Secondly, each js file has a set of enumerated functions that follow the boilerplate. What is this format and why are the functions in such a structure?

})()({
1: [function(a) {
    const b = a("./modules/config"),
        c = a("./modules/utils"),
        d = {};
    window.audioStates = d;

    ...

}, {
        "./modules/config": 2,
        "./modules/utils": 3
    }],

Then

2: [function(a, b) {
        b.exports = {