FileSystem module reference

The fs/promises module provides utilities for working with files and can be accessed using an import:

import { readFile } from 'fs/promises';

const content = await readFile('./foo.txt', 'utf8');

Functions

appendFile()

Call Signature

function appendFile(
   path: string, 
   data: string, 
encodingName?: string): Promise<void>;

Appends data to a file, replacing the file if it already exists.

Parameters

Parameter	Type	Description
path	string	The path to the file.
data	string	The data to Append.
encodingName?	string	The encoding to use.

Returns

Promise<void>

Call Signature

function appendFile(
   path: string, 
   data: string, 
options: FileAppendOptions): Promise<void>;

Appends data to a file.

Parameters

Parameter	Type	Description
path	string	The path to the file.
data	string	The data to Append.
options	FileAppendOptions	The options.

Returns

Promise<void>

Call Signature

function appendFile(path: string, data: Uint8Array): Promise<void>;

Appends data to a file, replacing the file if it already exists.

Parameters

Parameter	Type	Description
path	string	The path to the file.
data	Uint8Array	The data to Append.

Returns

Promise<void>

Call Signature

function appendFile(
   path: string, 
   data: Uint8Array, 
options: FileAppendOptions): Promise<void>;

Appends data to a file, replacing the file if it already exists (depending on options.flag).

Parameters

Parameter	Type	Description
path	string	The path to the file.
data	Uint8Array	The data to Append.
options	FileAppendOptions	The options.

Returns

Promise<void>

Call Signature

function appendFile(
   path: string, 
   data: Uint8Array, 
options: FileAppendOptions): Promise<void>;

Appends data to a file, replacing the file if it already exists (depending on options.flag).

Parameters

Parameter	Type	Description
path	string	The path to the file.
data	Uint8Array	The data to Append.
options	FileAppendOptions	The options.

Returns

Promise<void>

---

readFile()

Call Signature

function readFile(path: string): Promise<Uint8Array>;

Reads the entire content of a file.

Parameters

Parameter	Type	Description
path	string	The path of the file.

Returns

Promise<Uint8Array>

The data of the file.

Call Signature

function readFile(path: string, encodingName: string): Promise<string>;

Reads the entire content of a file.

Parameters

Parameter	Type	Description
path	string	The path of the file.
encodingName	string	The name of the encoding.

Returns

Promise<string>

The contents of the file.

Call Signature

function readFile(path: string, options: FileReadOptions): Promise<Uint8Array> | Promise<string>;

Reads the entire content of a file.

Parameters

Parameter	Type	Description
path	string	The path of the file.
options	FileReadOptions	The options to read the file.

Returns

Promise<Uint8Array> | Promise<string>

The file content as string if an encoding is provided, as Uint8Array otherwise.

---

writeFile()

Call Signature

function writeFile(
   path: string, 
   data: string, 
encodingName?: string): Promise<void>;

Writes data to a file, replacing the file if it already exists.

Parameters

Parameter	Type	Description
path	string	The path to the file.
data	string	The data to write.
encodingName?	string	The encoding to use.

Returns

Promise<void>

Call Signature

function writeFile(
   path: string, 
   data: string, 
options: FileWriteOptions): Promise<void>;

Writes data to a file, replacing the file if it already exists (depending on options.flag).

Parameters

Parameter	Type	Description
path	string	The path to the file.
data	string	The data to write.
options	FileWriteOptions	The options.

Returns

Promise<void>

Call Signature

function writeFile(path: string, data: Uint8Array): Promise<void>;

Writes data to a file, replacing the file if it already exists.

Parameters

Parameter	Type	Description
path	string	The path to the file.
data	Uint8Array	The data to write.

Returns

Promise<void>

Call Signature

function writeFile(
   path: string, 
   data: Uint8Array, 
options: FileWriteOptions): Promise<void>;

Writes data to a file, replacing the file if it already exists (depending on options.flag).

Parameters

Parameter	Type	Description
path	string	The path to the file.
data	Uint8Array	The data to write.
options	FileWriteOptions	The options.

Returns

Promise<void>

Call Signature

function writeFile(
   path: string, 
   data: Uint8Array, 
options: FileWriteOptions): Promise<void>;

Writes data to a file, replacing the file if it already exists (depending on options.flag).

Parameters

Parameter	Type	Description
path	string	The path to the file.
data	Uint8Array	The data to write.
options	FileWriteOptions	The options.

Returns

Promise<void>

Type Aliases

FileAppendOptions

type FileAppendOptions = {
  encoding: string;
  flag: string;
};

Options to append to files.

Properties

encoding?

optional encoding: string;

The name of the encoding.

flag?

optional flag: string;

The file system flags.

---

FileReadOptions

type FileReadOptions = {
  encoding: string;
};

Options when reading a file.

Properties

encoding?

optional encoding: string;

The encoding.

---

FileWriteOptions

type FileWriteOptions = {
  encoding: string;
  flag: string;
};

Options to write files.

Properties

encoding?

optional encoding: string;

The name of the encoding.

flag?

optional flag: string;

The file system flags.