# 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.
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