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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 licenced under the MIT licence. All rights not explicitly granted in the MIT license are reserved. See the included file for more details.