# is-stream > Check if something is a [Node.js stream](https://nodejs.org/api/stream.html) ## Install ``` $ npm install is-stream ``` ## Usage ```js const fs = require('fs'); const isStream = require('is-stream'); isStream(fs.createReadStream('unicorn.png')); //=> true isStream({}); //=> false ``` ## API ### isStream(stream) Returns a `boolean` for whether it's a [`Stream`](https://nodejs.org/api/stream.html#stream_stream). #### isStream.writable(stream) Returns a `boolean` for whether it's a [`stream.Writable`](https://nodejs.org/api/stream.html#stream_class_stream_writable). #### isStream.readable(stream) Returns a `boolean` for whether it's a [`stream.Readable`](https://nodejs.org/api/stream.html#stream_class_stream_readable). #### isStream.duplex(stream) Returns a `boolean` for whether it's a [`stream.Duplex`](https://nodejs.org/api/stream.html#stream_class_stream_duplex). #### isStream.transform(stream) Returns a `boolean` for whether it's a [`stream.Transform`](https://nodejs.org/api/stream.html#stream_class_stream_transform). ## Related - [is-file-stream](https://github.com/jamestalmage/is-file-stream) - Detect if a stream is a file stream ---

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