"exports is not defined" - using Foundation plugins with Babel - laravel-5

Question

I am new to foundation, and Babel, but have followed the docs and can't figure out what's wrong.
I am using Laravel Mix as part of my build system, which is basically a wrapper for Webpack. Here is my webpack.mix.js:
mix.babel([
'bower_components/jquery/dist/jquery.js',
'bower_components/foundation-sites/js/foundation.dropdownMenu.js',
'resources/assets/themes/'+themeInfo.name+'/js/app.js'
], 'public/themes/'+themeInfo.name+'/js/all.js');
The build process appears to run just fine, however I am getting "Uncaught ReferenceError: exports is not defined" in the browser.
At the top of all.js I can see the following JS:
"use strict";
Object.defineProperty(exports, "__esModule", {
value: true
});
exports.DropdownMenu = undefined;
var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();
var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) { return typeof obj; } : function (obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; };
var _jquery = require("jquery");
var _jquery2 = _interopRequireDefault(_jquery);
var _foundationUtil = require("./foundation.util.keyboard");
var _foundationUtil2 = require("./foundation.util.nest");
var _foundationUtil3 = require("./foundation.util.box");
var _foundationUtil4 = require("./foundation.util.core");
var _foundation = require("./foundation.plugin");
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
function _possibleConstructorReturn(self, call) { if (!self) { throw new ReferenceError("this hasn't been initialised - super() hasn't been called"); } return call && (typeof call === "object" || typeof call === "function") ? call : self; }
function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass; }
To test, I declared the exports variable `var exports = {};` at the top of the file, which only then resulted in the error "Uncaught ReferenceError: require is not defined" pointing to the "var _jquery = require("jquery");" declaration.
I suspect I'm not understanding how Babel/Foundation plugins work properly, so any help would be appreciated please.
BTW I have the following in my .babelrc file, and have installed the preset using npm install babel-preset-es2015 --save-dev:
{
"presets": ["es2015"]
}