# isStream [](http://travis-ci.org/rvagg/isstream) **Test if an object is a `Stream`** [](https://nodei.co/npm/isstream/) 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](https://github.com/isaacs/readable-stream)**. ## Usage: ```js 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. ```js 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](http://r.va.gg/2014/06/why-i-dont-use-nodes-core-stream-module.html).* ## License **isStream** is Copyright (c) 2015 Rod Vagg [@rvagg](https://twitter.com/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.