webpack/lib/prepareOptions.js

"use strict";

const handleExport = options => {
	const isES6DefaultExported = (
		typeof options === "object" && options !== null && typeof options.default !== "undefined"
	);
	options = isES6DefaultExported ? options.default : options;
	return options;
};

const handleFunction = (options, argv) => {
	if(typeof options === "function") {
		options = options(argv.env, argv);
	}
	return options;
};

module.exports = (options, argv) => {
	argv = argv || {};

	options = handleExport(options);

	if(Array.isArray(options)) {
		options = options.map(_options => handleFunction(_options, argv));
	} else {
		options = handleFunction(options, argv);
	}
	return options;
};