Function basename

lib/path.js:899–980

* @param {string} path * @param {string} [suffix] * @returns {string}

(path, suffix)

   * @returns {string}
   */
  basename(path, suffix) {
    if (suffix !== undefined)
      validateString(suffix, 'suffix');
    validateString(path, 'path');
    let start = 0;
    let end = -1;
    let matchedSlash = true;

    // Check for a drive letter prefix so as not to mistake the following
    // path separator as an extra separator at the end of the path that can be
    // disregarded
    if (path.length >= 2 &&
        isWindowsDeviceRoot(StringPrototypeCharCodeAt(path, 0)) &&
        StringPrototypeCharCodeAt(path, 1) === CHAR_COLON) {
      start = 2;
    }

    if (suffix !== undefined && suffix.length > 0 && suffix.length <= path.length) {
      if (suffix === path)
        return '';
      let extIdx = suffix.length - 1;
      let firstNonSlashEnd = -1;
      for (let i = path.length - 1; i >= start; --i) {
        const code = StringPrototypeCharCodeAt(path, i);
        if (isPathSeparator(code)) {
          // If we reached a path separator that was not part of a set of path
          // separators at the end of the string, stop now
          if (!matchedSlash) {
            start = i + 1;
            break;
          }
        } else {
          if (firstNonSlashEnd === -1) {
            // We saw the first non-path separator, remember this index in case
            // we need it if the extension ends up not matching
            matchedSlash = false;
            firstNonSlashEnd = i + 1;
          }
          if (extIdx >= 0) {
            // Try to match the explicit extension
            if (code === StringPrototypeCharCodeAt(suffix, extIdx)) {
              if (--extIdx === -1) {
                // We matched the extension, so mark this as the end of our path
                // component
                end = i;
              }
            } else {
              // Extension does not match, so our result is the entire path
              // component
              extIdx = -1;
              end = firstNonSlashEnd;
            }
          }
        }
      }

      if (start === end)
        end = firstNonSlashEnd;