index.d.ts

import {
	type Stream,
	type Writable as WritableStream,
	type Readable as ReadableStream,
	type Duplex as DuplexStream,
	type Transform as TransformStream,
} from 'node:stream';

export type Options = {
	/**
	When this option is `true`, the method returns `false` if the stream has already been closed.

	@default true
	*/
	checkOpen?: boolean;
};

/**
@returns Whether `stream` is a [`Stream`](https://nodejs.org/api/stream.html#stream_stream).

@example
```
import fs from 'node:fs';
import {isStream} from 'is-stream';

isStream(fs.createReadStream('unicorn.png'));
//=> true

isStream({});
//=> false
```
*/
export function isStream(stream: unknown, options?: Options): stream is Stream;

/**
@returns Whether `stream` is a [`stream.Writable`](https://nodejs.org/api/stream.html#stream_class_stream_writable), an [`http.OutgoingMessage`](https://nodejs.org/api/http.html#class-httpoutgoingmessage), an [`http.ServerResponse`](https://nodejs.org/api/http.html#class-httpserverresponse) or an [`http.ClientRequest`](https://nodejs.org/api/http.html#class-httpserverresponse).

@example
```
import fs from 'node:fs';
import {isWritableStream} from 'is-stream';

isWritableStream(fs.createWriteStrem('unicorn.txt'));
//=> true
```
*/
export function isWritableStream(stream: unknown, options?: Options): stream is WritableStream;

/**
@returns Whether `stream` is a [`stream.Readable`](https://nodejs.org/api/stream.html#stream_class_stream_readable) or an [`http.IncomingMessage`](https://nodejs.org/api/http.html#class-httpincomingmessage).

@example
```
import fs from 'node:fs';
import {isReadableStream} from 'is-stream';

isReadableStream(fs.createReadStream('unicorn.png'));
//=> true
```
*/
export function isReadableStream(stream: unknown, options?: Options): stream is ReadableStream;

/**
@returns Whether `stream` is a [`stream.Duplex`](https://nodejs.org/api/stream.html#stream_class_stream_duplex).

@example
```
import {Duplex as DuplexStream} from 'node:stream';
import {isDuplexStream} from 'is-stream';

isDuplexStream(new DuplexStream());
//=> true
```
*/
export function isDuplexStream(stream: unknown, options?: Options): stream is DuplexStream;

/**
@returns Whether `stream` is a [`stream.Transform`](https://nodejs.org/api/stream.html#stream_class_stream_transform).

@example
```
import fs from 'node:fs';
import StringifyStream from 'streaming-json-stringify';
import {isTransformStream} from 'is-stream';

isTransformStream(StringifyStream());
//=> true
```
*/
export function isTransformStream(stream: unknown, options?: Options): stream is TransformStream;