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read - fs - Node documentation
function read

Usage in Deno

import { read } from "node:fs";
read<TBuffer extends ArrayBufferView>(
fd: number,
buffer: TBuffer,
offset: number,
length: number,
position: ReadPosition | null,
callback: (
err: ErrnoException | null,
bytesRead: number,
buffer: TBuffer,
) => void
,
): void

Read data from the file specified by fd.

The callback is given the three arguments, (err, bytesRead, buffer).

If the file is not modified concurrently, the end-of-file is reached when the number of bytes read is zero.

If this method is invoked as its util.promisify() ed version, it returns a promise for an Object with bytesRead and buffer properties.

Type Parameters

TBuffer extends ArrayBufferView

Parameters

fd: number
buffer: TBuffer

The buffer that the data will be written to.

offset: number

The position in buffer to write the data to.

length: number

The number of bytes to read.

position: ReadPosition | null

Specifies where to begin reading from in the file. If position is null or -1 , data will be read from the current file position, and the file position will be updated. If position is an integer, the file position will be unchanged.

callback: (
err: ErrnoException | null,
bytesRead: number,
buffer: TBuffer,
) => void

Return Type

void
read<TBuffer extends ArrayBufferView>(
fd: number,
options: ReadAsyncOptions<TBuffer>,
callback: (
err: ErrnoException | null,
bytesRead: number,
buffer: TBuffer,
) => void
,
): void

Similar to the above fs.read function, this version takes an optional options object. If not otherwise specified in an options object, buffer defaults to Buffer.alloc(16384), offset defaults to 0, length defaults to buffer.byteLength, - offset as of Node 17.6.0 position defaults to null

Type Parameters

TBuffer extends ArrayBufferView

Parameters

fd: number
callback: (
err: ErrnoException | null,
bytesRead: number,
buffer: TBuffer,
) => void

Return Type

void
read(
fd: number,
callback: (
err: ErrnoException | null,
bytesRead: number,
buffer: ArrayBufferView,
) => void
,
): void

Parameters

fd: number
callback: (
err: ErrnoException | null,
bytesRead: number,
buffer: ArrayBufferView,
) => void

Return Type

void