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https://github.com/thlorenz/nebraska
Streams the state of another stream.
https://github.com/thlorenz/nebraska
Last synced: 26 days ago
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Streams the state of another stream.
- Host: GitHub
- URL: https://github.com/thlorenz/nebraska
- Owner: thlorenz
- License: mit
- Created: 2013-09-10T09:39:26.000Z (over 11 years ago)
- Default Branch: master
- Last Pushed: 2013-12-12T02:46:05.000Z (about 11 years ago)
- Last Synced: 2024-10-23T06:17:09.740Z (2 months ago)
- Language: JavaScript
- Homepage:
- Size: 160 KB
- Stars: 2
- Watchers: 2
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# nebraska [](http://travis-ci.org/thlorenz/nebraska)
Streams the state of another stream.
```js
var nebraska = require('nebraska');
var numbers = require('../test/fixtures/number-readable');
var powers = require('../test/fixtures/power-transform');
// the numbers readable emits numbers faster than the powers transfom
// can handle them (simulated via throttle settings)
var readable = numbers({ to: 10, throttle: 100, objectMode: true, highWaterMark: 0 })
, transform = powers({ throttle: 400, objectMode: true, highWaterMark: 4 })
var numbersState = nebraska(readable, { interval: 400 })
, powersState = nebraska(transform, { interval: 400 })
readable
.on('data', function (d) { console.log('Emitted: ', d.toString()) })
.on('end', numbersState.endSoon.bind(numbersState))
.pipe(transform)
.on('data', function (d) { console.log('Transformed: ', d.toString()) })
.on('end', powersState.endSoon.bind(powersState))
numbersState.on('data', console.log.bind(console));
powersState.on('data', console.log.bind(console));
```
#### Output:
The below shows that buffer is filled to `highWaterMark` and drained while the faster number stream gets paused
due to backpressure.
**Note:** the last part of the output was omitted for brevity.
```sh
Emitted: 0
Emitted: 1
Emitted: 2
Emitted: 3
{ label: 'NumberReadable(S)',
readable: { highWaterMark: 0, bufferLength: 0 } }
{ label: 'PowerTransform(S)',
readable: { highWaterMark: 4, bufferLength: 0 },
writable: { highWaterMark: 4, bufferLength: 3 } }
Transformed: 0
{ label: 'NumberReadable(S)',
readable: { highWaterMark: 0, bufferLength: 1 } }
{ label: 'PowerTransform(S)',
readable: { highWaterMark: 4, bufferLength: 0 },
writable: { highWaterMark: 4, bufferLength: 2 } }
Transformed: 1
{ label: 'NumberReadable(S)',
readable: { highWaterMark: 0, bufferLength: 1 } }
{ label: 'PowerTransform(S)',
readable: { highWaterMark: 4, bufferLength: 0 },
writable: { highWaterMark: 4, bufferLength: 1 } }
Transformed: 4
{ label: 'NumberReadable(S)',
readable: { highWaterMark: 0, bufferLength: 1 } }
{ label: 'PowerTransform(S)',
readable: { highWaterMark: 4, bufferLength: 0 },
writable: { highWaterMark: 4, bufferLength: 0 } }
Transformed: 9
Emitted: 4
Emitted: 5
Emitted: 6
Emitted: 7
{ label: 'NumberReadable(S)',
readable: { highWaterMark: 0, bufferLength: 0 } }
{ label: 'PowerTransform(S)',
readable: { highWaterMark: 4, bufferLength: 0 },
writable: { highWaterMark: 4, bufferLength: 3 } }
Transformed: 16
[ ... ]
```
## Installation
npm install nebraska
## API
###*nebraska(stream[, opts])*
```
/**
* Creates a readable stream that streams readable/writable state changes of the given stream.
*
* @name WatcherReadable
* @function
* @param stream {Stream} a readable and/or writable stream whose states to stream
* @param opts {Object} with the following properties
* - interval {Number} the millisecond interval at which state updates are streamed (default: 500)
* - readable {Array[String]} names of readable properties that should be included in the state stream (default: highWaterMark, bufferLength)
* - writable {Array[String]} names of writable properties that should be included in the state stream (default: highWaterMark, bufferLength)
* - label {String} label that is emitted with every state update (default: the name of the stream constructor + (S))
* @return {Stream} WatcherReadable that emits state updates.
*/
```
###*WatcherReadable.endSoon*
```
/**
* Call this in case you want to tell the state stream to end.
* Useful for testing and/or when you want to end your debugging session and allow the program to exit.
*/
```
###*nebraska.properties*
```
/**
* Arrays of all property names for each type of stream which make sense to be included in state updates.
* @return {Object} with the following properties
* - readable: {Array[String]} properties of the stream.readableState
* - writable: {Array[String]} properties of the stream.writableState
*/
```
## Why the name Nebraska?
Because it has more streams than Montana.
## License
MIT