98 lines
2.6 KiB
Markdown
98 lines
2.6 KiB
Markdown
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# duplexify
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Turn a writeable and readable stream into a single streams2 duplex stream.
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Similar to [duplexer2](https://github.com/deoxxa/duplexer2) except it supports both streams2 and streams1 as input
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and it allows you to set the readable and writable part asynchroniously using `setReadable(stream)` and `setWritable(stream)`
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```
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npm install duplexify
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```
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[](http://travis-ci.org/mafintosh/duplexify)
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## Usage
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Use `duplexify(writable, readable, streamOptions)` (or `duplexify.obj(writable, readable)` to create an object stream)
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``` js
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var duplexify = require('duplexify')
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// turn writableStream and readableStream into a single duplex stream
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var dup = duplexify(writableStream, readableStream)
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dup.write('hello world') // will write to writableStream
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dup.on('data', function(data) {
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// will read from readableStream
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})
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```
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You can also set the readable and writable parts asynchroniously
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``` js
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var dup = duplexify()
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dup.write('hello world') // write will buffer until the writable
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// part has been set
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// wait a bit ...
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dup.setReadable(readableStream)
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// maybe wait some more?
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dup.setWritable(writableStream)
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```
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If you call `setReadable` or `setWritable` multiple times it will unregister the previous readable/writable stream.
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To disable the readable or writable part call `setReadable` or `setWritable` with `null`.
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If the readable or writable streams emits an error or close it will destroy both streams and bubble up the event.
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You can also explictly destroy the streams by calling `dup.destroy()`. The `destroy` method optionally takes an
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error object as argument, in which case the error is emitted as part of the `error` event.
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``` js
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dup.on('error', function(err) {
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console.log('readable or writable emitted an error - close will follow')
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})
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dup.on('close', function() {
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console.log('the duplex stream is destroyed')
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})
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dup.destroy() // calls destroy on the readable and writable part (if present)
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```
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## HTTP request example
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Turn a node core http request into a duplex stream is as easy as
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``` js
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var duplexify = require('duplexify')
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var http = require('http')
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var request = function(opts) {
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var req = http.request(opts)
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var dup = duplexify(req)
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req.on('response', function(res) {
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dup.setReadable(res)
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})
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return dup
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}
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var req = request({
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method: 'GET',
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host: 'www.google.com',
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port: 80
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})
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req.end()
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req.pipe(process.stdout)
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```
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## License
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MIT
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## Related
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`duplexify` is part of the [mississippi stream utility collection](https://github.com/maxogden/mississippi) which includes more useful stream modules similar to this one.
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