333

schangxiang@126.com

2025-09-19 18966e02fb573c7e2bb0c6426ed792b38b910940

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
# isStream
 
[![Build Status](https://secure.travis-ci.org/rvagg/isstream.png)](http://travis-ci.org/rvagg/isstream)
 
**Test if an object is a `Stream`**
 
[![NPM](https://nodei.co/npm/isstream.svg)](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.