Function extname

lib/ManifestPlugin.js:35–43

(filename)

 * @returns {string} extname
 */
const extname = (filename) => {
	const replaced = filename.replace(/\?.*/, "");
	const split = replaced.split(".");
	const last = split.pop();
	if (!last) return "";
	return last && /^(?:gz|br|map)$/i.test(last)
		? `${split.pop()}.${last}`
		: last;
};

const DEFAULT_PREFIX = "[publicpath]";
const DEFAULT_FILENAME = "manifest.json";