Skip to content
Branch: master
Go to file

Latest commit

rvagg committed 52901ef Dec 30, 2015
Merge pull request #5 from RossGammon/spelling
Fix spelling error in, licence/licencing > license/licensing


Failed to load latest commit information.
Latest commit message
Commit time


Build Status

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.


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.


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

You can’t perform that action at this time.