node-red source code

liudong

2023-05-29 340f156319b863525e50e900c58e59b86ecb3d5e

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[![view on npm](http://img.shields.io/npm/v/stream-connect.svg)](https://www.npmjs.org/package/stream-connect)
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# stream-connect
 
Similar to `.pipe` except `.pipe` returns the last stream in a pipeline. stream-connect returns a stream which writes to the first stream in the pipeline and reads from the last.
 
## Synopsis
 
```js
const connect = require('stream-connect')
const fs = require('fs')
 
const connected = connect(stream1, stream2, stream3, stream4)
 
// data piped into the connected stream is transparently passed through all four internal streams
// then output into process.stdout. Errors in any of the internal streams are emitted
// by the connected stream.
process.stdin
  .pipe(connected)
  .on('error', console.error)
  .pipe(process.stdout)
```
 
## More detail
 
Consider this `.pipe` example.
 
```js
function getExampleStream () {
 ...
 return streamOne.pipe(streamTwo)
}
const stream = getExampleStream()
stream.on('data', function (chunk) {}) // catches data from streamOne via streamTwo
stream.on('error', function (err) {}) // catches errors only from streamTwo
stream.end('test') // is written to streamTwo
```
 
If you write to the output it will be written to `streamTwo`, whereas you probably wanted to write to the  start of the pipeline and read from the end. Fixed by stream-connect:
 
```js
const connect = require('stream-connect')
function getExampleStream () {
 ...
 return connect(streamOne, streamTwo)
}
const stream = getExampleStream()
stream.on('data', function (chunk) {}) // catches data from streamOne via streamTwo
stream.on('error', function (err) {}) // catches errors from both streamOne and streamTwo
stream.end('test') // is written to streamOne
```
 
Any errors emitted in `streamOne` or `streamTwo` are propagated to the output stream.
 
{{>main}}
 
* * *
 
&copy; 2015 Lloyd Brookes \<75pound@gmail.com\>. Documented by [jsdoc-to-markdown](https://github.com/jsdoc2md/jsdoc-to-markdown).