isstream

What is isstream?

The isstream npm package is a simple utility to check if an object is a stream. It provides functions to determine if an object is a readable, writable, or duplex stream.

What are isstream's main functionalities?

Check if an object is a stream

This feature allows you to check if a given object is a stream. In this example, we use the fs module to create a readable stream and then check if it is a stream using isStream.

const isStream = require('isstream');
const fs = require('fs');

const readableStream = fs.createReadStream('example.txt');
console.log(isStream(readableStream)); // true

Check if an object is a readable stream

This feature allows you to check if a given object is a readable stream. In this example, we use the fs module to create a readable stream and then check if it is a readable stream using isStream.isReadable.

const isStream = require('isstream');
const fs = require('fs');

const readableStream = fs.createReadStream('example.txt');
console.log(isStream.isReadable(readableStream)); // true

Check if an object is a writable stream

This feature allows you to check if a given object is a writable stream. In this example, we use the fs module to create a writable stream and then check if it is a writable stream using isStream.isWritable.

const isStream = require('isstream');
const fs = require('fs');

const writableStream = fs.createWriteStream('example.txt');
console.log(isStream.isWritable(writableStream)); // true

Check if an object is a duplex stream

This feature allows you to check if a given object is a duplex stream. In this example, we create a duplex stream using the stream module and then check if it is a duplex stream using isStream.isDuplex.

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

const duplexStream = new Duplex();
console.log(isStream.isDuplex(duplexStream)); // true

Other packages similar to isstream

is-stream

The is-stream package provides similar functionality to isstream, allowing you to check if an object is a stream, readable stream, writable stream, or duplex stream. It is a lightweight and straightforward alternative.

stream

The stream package is part of Node.js core and provides a comprehensive API for working with streams. While it does not provide simple type-checking functions like isstream, it offers extensive functionality for creating and managing streams.

through2

The through2 package is a tiny wrapper around Node.js streams2 Transform to avoid explicit subclassing noise. It is more focused on stream transformation but can be used in conjunction with isstream for type-checking.

README

isStream

Test if an object is a Stream

The missing Stream.isStream(obj): determine if an object is standard Node.js Stream. Works for Node-core Stream objects (for 0.8, 0.10, 0.11, and in theory, older and newer versions) and all versions of readable-stream.

Usage:

var isStream = require('isstream')
var Stream = require('stream')

isStream(new Stream()) // true

isStream({}) // false

isStream(new Stream.Readable())    // true
isStream(new Stream.Writable())    // true
isStream(new Stream.Duplex())      // true
isStream(new Stream.Transform())   // true
isStream(new Stream.PassThrough()) // true

But wait! There's more!

You can also test for isReadable(obj), isWritable(obj) and isDuplex(obj) to test for implementations of Streams2 (and Streams3) base classes.

var isReadable = require('isstream').isReadable
var isWritable = require('isstream').isWritable
var isDuplex = require('isstream').isDuplex
var Stream = require('stream')

isReadable(new Stream()) // false
isWritable(new Stream()) // false
isDuplex(new Stream())   // false

isReadable(new Stream.Readable())    // true
isReadable(new Stream.Writable())    // false
isReadable(new Stream.Duplex())      // true
isReadable(new Stream.Transform())   // true
isReadable(new Stream.PassThrough()) // true

isWritable(new Stream.Readable())    // false
isWritable(new Stream.Writable())    // true
isWritable(new Stream.Duplex())      // true
isWritable(new Stream.Transform())   // true
isWritable(new Stream.PassThrough()) // true

isDuplex(new Stream.Readable())    // false
isDuplex(new Stream.Writable())    // false
isDuplex(new Stream.Duplex())      // true
isDuplex(new Stream.Transform())   // true
isDuplex(new Stream.PassThrough()) // true

Reminder: when implementing your own streams, please use readable-stream rather than core streams.

License

isStream is Copyright (c) 2015 Rod Vagg @rvagg and licenced under the MIT licence. All rights not explicitly granted in the MIT license are reserved. See the included LICENSE.md file for more details.