FS API
Interface: FileSystem
The File System API provides the ability to read and write files.
It is design to be compatible with the Node.js File System API.
import { readFileSync } from "fs";
let text = readFileSync("my_file.txt", "utf-8");
console.log(text);
Find out more about this API in the File System Guide
existsSync()
New in SDK 4.0
Test whether or not the given path exists and is accessible through the filesystem.
fs.existsSync(path: string)
Parameters
path: string
Name of path to check for existence.
writeFileSync()
Write data to a file in a single operation. If a file with that name already exists, it is overwritten; otherwise, a new file is created.
fs.writeFileSync(filename: string, data: ArrayBuffer | ArrayBufferView)
Parameters
filename: string
Name of the file to write.
data: ArrayBuffer or ArrayBufferView
With no encoding specified, data is a binary data buffer.
With encoding == "ascii" or "utf-8", data is a string that will be
serialized with the respective encoding. With encoding == "cbor" or
"json", data is an object that will be serialized with CBOR or
JSON encoding, respectively.
fs.writeFileSync(filename: string, data: string, encoding: "ascii" | "utf-8")
Parameters
filename: string
data: string
encoding: "ascii" or "utf-8"
fs.writeFileSync(filename: string, data: any, encoding: "cbor" | "json")
Parameters
filename: string
data: any
encoding: "cbor" or "json"
readFileSync()
Read an entire file into a buffer in a single operation.
fs.readFileSync(filename: string)
Parameters
filename: string
Name of the file to read.
fs.readFileSync(filename: string, encoding: "ascii" | "utf-8")
Parameters
filename: string
encoding: "ascii" or "utf-8"
fs.readFileSync(filename: string, encoding: "cbor" | "json")
Parameters
filename: string
encoding: "cbor" or "json"
renameSync()
Rename a file.
fs.renameSync(oldFilename: string, newFilename: string)
Parameters
oldFilename: string
Name of the file to be renamed.
newFilename: string
Name to which the filename should be changed.
unlinkSync()
Delete a file.
fs.unlinkSync(filename: string)
Parameters
filename: string
Name of the file to be deleted.
statSync()
Get metadata of a file.
fs.statSync(filename: string)
Parameters
filename: string
Name of the file of which the metadata is requested.
writeSync()
Write buffer to the file specified by fd.
fs.writeSync(fd: number, buffer: ArrayBuffer, offset?: number | undefined, length?: number | undefined, position?: number | undefined)
Parameters
fd: number
File descriptor to which to write.
buffer: ArrayBuffer
Buffer containing the data to write.
(optional) offset: number or undefined
Offset in buffer of the first byte of data to write.
(default: 0)
(optional) length: number or undefined
Number of bytes to write. (default: the size of the buffer)
(optional) position: number or undefined
Offset from the beginning of the file where the data
should be written. If the file was opened in append mode (a or a+),
this parameter is ignored.
readSync()
Read data from the file specified by fd.
fs.readSync(fd: number, buffer: ArrayBuffer, offset?: number | undefined, length?: number | undefined, position?: number | undefined)
Parameters
fd: number
File descriptor from which to read.
buffer: ArrayBuffer
Buffer in which to store the read data.
(optional) offset: number or undefined
Offset in buffer of the first byte where the file data is
to be stored. (default: 0)
(optional) length: number or undefined
Number of bytes to read. (default: the size of the buffer)
(optional) position: number or undefined
Offset from the beginning of the file from which the data
should be read. (default: 0)
closeSync()
Close a file descriptor.
fs.closeSync(fd: number)
Parameters
fd: number
File descriptor for the file to close.
openSync()
Open a file.
Filenames are flat names without hierarchy and cannot contain path
separators (/) or prefixes.
A filename is a non-empty string of up to 64 characters
Valid characters for filenames are: a-z, A-Z, 0-9, !, #,
$, %, &, ', (, ), -, @, ^, _, {, }, ~, .,
The reserved names . and .. are not allowed as filenames.
fs.openSync(filename: string, flags: "r" | "r+" | "w" | "w+" | "a" | "a+")
Parameters
filename: string
Name of the file to open.
flags: "r" or "r+" or "w" or "w+" or "a" or "a+"
Flags that specify the mode with which to open the file.
r: Open the file for reading. An error is thrown if the file does not exist.r+: Open the file for reading and writing. An error is thrown if the file does not exist.w: Open the file for writing. The file is created if it does not exist or truncated if it does.w+: Open the file for reading and writing. The file is created if it does not exist or truncated if it does.a: Open the file for appending. The file is created if it does not exist.a+: Open the file for reading and appending. The file is created if it does not exist.
listDirSync()
New in SDK 2.0
Method to initiate the process of non-recursively listing all items in a given directory.
fs.listDirSync(path: string)
Parameters
path: string
Path to read from.
Interface: DirectoryIteratorResult
DirectoryIteratorResult
Properties
readonly done
boolean
boolean indicating whether we are done iterating
readonly value
string or undefined
name of current directory entry or undefined if done is true
Interface: DirectoryIterator
Directory
Methods
next()
Returns: DirectoryIteratorResult
Retrieve the next directory entry
Interface: FileStats
File metadata
Properties
readonly mtime
Date
Time at which the file data was last modified.
readonly size
number
Size of the file in bytes.
