• Asynchronously reads the entire contents of a file.

    If no encoding is specified (using options.encoding), the data is returned as a Buffer object. Otherwise, the data will be a string.

    If options is a string, then it specifies the encoding.

    When the path is a directory, the behavior of fsPromises.readFile() is platform-specific. On macOS, Linux, and Windows, the promise will be rejected with an error. On FreeBSD, a representation of the directory's contents will be returned.

    It is possible to abort an ongoing readFile using an AbortSignal. If a request is aborted the promise returned is rejected with an AbortError:

    import { readFile } from 'fs/promises';

    try {
    const controller = new AbortController();
    const { signal } = controller;
    const promise = readFile(fileName, { signal });

    // Abort the request before the promise settles.
    controller.abort();

    await promise;
    } catch (err) {
    // When a request is aborted - err is an AbortError
    console.error(err);
    }

    Aborting an ongoing request does not abort individual operating system requests but rather the internal buffering fs.readFile performs.

    Any specified FileHandle has to support reading.

    Since

    v10.0.0

    Returns

    Fulfills with the contents of the file.

    Parameters

    Returns Promise<Buffer>

  • Asynchronously reads the entire contents of a file.

    Parameters

    • path: PathLike | FileHandle

      A path to a file. If a URL is provided, it must use the file: protocol. If a FileHandle is provided, the underlying file will not be closed automatically.

    • options: BufferEncoding | {
          encoding: BufferEncoding;
          flag?: OpenMode;
      } & Abortable

      An object that may contain an optional flag. If a flag is not provided, it defaults to 'r'.

    Returns Promise<string>

  • Asynchronously reads the entire contents of a file.

    Parameters

    • path: PathLike | FileHandle

      A path to a file. If a URL is provided, it must use the file: protocol. If a FileHandle is provided, the underlying file will not be closed automatically.

    • Optional options: null | BufferEncoding | ObjectEncodingOptions & Abortable & {
          flag?: OpenMode;
      }

      An object that may contain an optional flag. If a flag is not provided, it defaults to 'r'.

    Returns Promise<string | Buffer>