is-stream

What is is-stream?

The is-stream npm package is a simple utility used to check if an object is a Node.js stream. It can differentiate between readable, writable, duplex (both readable and writable), and transform (a type of duplex stream) streams. This package is useful when you need to validate that a given object conforms to the stream interface expected by Node.js APIs.

What are is-stream's main functionalities?

Check if an object is a stream

This feature allows you to check if a given object is a Node.js stream.

const isStream = require('is-stream');

isStream(process.stdin); // true
isStream({}); // false

Check if a stream is readable

This feature allows you to check if a stream is a readable stream.

const isStream = require('is-stream');

isStream.readable(process.stdin); // true
isStream.readable(process.stdout); // false

Check if a stream is writable

This feature allows you to check if a stream is a writable stream.

const isStream = require('is-stream');

isStream.writable(process.stdout); // true
isStream.writable(process.stdin); // false

Check if a stream is a duplex stream

This feature allows you to check if a stream is a duplex stream, which is both readable and writable.

const isStream = require('is-stream');
const { Duplex } = require('stream');

const duplexStream = new Duplex();
isStream.duplex(duplexStream); // true
isStream.duplex(process.stdin); // false

Check if a stream is a transform stream

This feature allows you to check if a stream is a transform stream, which is a type of duplex stream with additional functionality.

const isStream = require('is-stream');
const { Transform } = require('stream');

const transformStream = new Transform();
isStream.transform(transformStream); // true
isStream.transform(process.stdin); // false

Other packages similar to is-stream

isstream

isstream is another package that provides a similar functionality to is-stream. It checks if an object is a stream. The main difference is in the implementation and the specific checks performed. is-stream is more up-to-date and has more downloads, suggesting it is more popular and potentially more reliable.

stream-assert

stream-assert is a package that provides a set of assertion functions for streams, which can be used in testing. While it includes functionality to assert the type of streams, it goes beyond just checking if an object is a stream by offering a suite of assertions for stream content and behavior.

README

is-stream

Check if something is a Node.js stream

Install

npm install is-stream

Usage

import fs from 'node:fs';
import {isStream} from 'is-stream';

isStream(fs.createReadStream('unicorn.png'));
//=> true

isStream({});
//=> false

API

isStream(stream, options?)

Returns a boolean for whether it's a Stream.

isWritableStream(stream, options?)

Returns a boolean for whether it's a stream.Writable, an http.OutgoingMessage, an http.ServerResponse or an http.ClientRequest.

isReadableStream(stream, options?)

Returns a boolean for whether it's a stream.Readable or an http.IncomingMessage.

isDuplexStream(stream, options?)

Returns a boolean for whether it's a stream.Duplex.

isTransformStream(stream, options?)

Returns a boolean for whether it's a stream.Transform.

Options

checkOpen

Type: boolean
Default: true

When this option is true, the method returns false if the stream has already been closed.

Related

• is-file-stream - Detect if a stream is a file stream