Function extname

lib/internal/modules/esm/get_format.js:117–129

* Returns the file extension from a URL. Should give similar result to * `require('node:path').extname(require('node:url').fileURLToPath(url))` * when used with a `file:` URL. * @param {URL} url * @returns {string}

(url)

 * @returns {string}
 */
function extname(url) {
  const { pathname } = url;
  for (let i = pathname.length - 1; i > 0; i--) {
    switch (StringPrototypeCharCodeAt(pathname, i)) {
      case SLASH_CODE:
        return '';

      case DOT_CODE:
        return StringPrototypeCharCodeAt(pathname, i - 1) === SLASH_CODE ? '' : StringPrototypeSlice(pathname, i);
    }
  }
  return '';
}

/**
 * Determine whether the given file URL is under a `node_modules` folder.