JavaScript Bilateral Module Loader (JS-BML) – the core of CrossCore (pun not intended)!

mloader.js

var AjaxRequest = null;

if ((typeof require) === 'undefined') {
    if ((typeof XMLHttpRequest) !== 'undefined')
        AjaxRequest = function () {
            return new XMLHttpRequest();
        };

    else if ((typeof ActiveXObject) !== 'undefined')
        AjaxRequest = function () {
            return new ActiveXObject("Microsoft.XMLHTTP");
        };

    else
        throw new Error('The CrossCore bilateral module loader needs an AJAX-capable JavaScript API on your browser, but neither XMLHttpRequest, nor ActiveXObject, were found. Try using a newer browser.');
}

var loader = {
    cache: {},
    root: ".",

    setRoot: function setRoot(root) {
        if ((typeof require) !== 'undefined')
            loader.root = root;
    },

    importModule: function importModule(modulePath, moduleName, callback, force) {
        if (Object.keys(loader.cache).indexOf(moduleName) > -1 && !force)
            callback(loader.cache[moduleName]);

        if ((typeof require) === 'undefined') {
            let req = new AjaxRequest();

            req.onreadystatechange = function () {
                if (this.readyState == 4 && this.status == 200) {
                    var mod = new Function("loader", this.responseText)(loader);

                    loader.cache[moduleName] = mod;
                    callback(mod);
                }
            };

            req.open("GET", modulePath, true);
            req.send();

        } else {
            var mod = new Function("loader", require('fs').readFileSync(require('path').join(loader.root, modulePath)))(loader);

            loader.cache[moduleName] = mod;
            callback(mod);
        }
    },

    importModuleSync: function importModule(modulePath, moduleName, force) {
        if (Object.keys(loader.cache).indexOf(moduleName) > -1 && !force)
            return loader.cache[moduleName];

        var mod;

        if ((typeof require) === 'undefined') {
            let req = new XMLHttpRequest();

            req.open("GET", modulePath, false);
            req.send();

            if (req.status == 200) {
                mod = new Function("loader", req.responseText)(loader);

                loader.cache[moduleName] = mod;
                return mod;
            }

            else
                return null;

        } else {
            mod = new Function("loader", require('fs').readFileSync(require('path').join(loader.root, modulePath)))(loader);

            loader.cache[moduleName] = mod;
            return mod;
        }
    },

    globalImport: function globalImport(modulePath, moduleName, force) {
        function callback(mod) {
            if ((typeof require) === 'undefined')
                window[moduleName] = mod;

            else
                global[moduleName] = mod;
        }

        importModule(modulePath, moduleName, callback, force);
    },

    globalImportSync: function globalImportSync(modulePath, moduleName, force) {
        function callback(mod) {
            if ((typeof require) === 'undefined')
                window[moduleName] = mod;

            else
                global[moduleName] = mod;
        }

        callback(importModuleSync(modulePath, moduleName, force));
    },
};

if ((typeof require) !== 'undefined') {
    require.modules = {};
    module.exports = loader;
} else
    window.loader = loader;