Function watch

lib/internal/vfs/setup.js:466–481

(filename, options, listener)

    // ==================== Watch ops ====================

    watch(filename, options, listener) {
      if (typeof options === 'function') {
        listener = options;
        options = kEmptyObject;
      } else if (options != null) {
        validateObject(options, 'options');
      } else {
        options = kEmptyObject;
      }
      const pathStr = toPathStr(filename);
      if (pathStr !== null) {
        const r = findVFSForPath(pathStr);
        if (r !== null) return r.vfs.watch(pathStr, options, listener);
      }
      return undefined;
    },

    // ==================== Async path-based ops ====================