87 lines
2.7 KiB
Markdown
87 lines
2.7 KiB
Markdown
# multistream [![travis][travis-image]][travis-url] [![npm][npm-image]][npm-url] [![downloads][downloads-image]][downloads-url] [![javascript style guide][standard-image]][standard-url]
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[travis-image]: https://img.shields.io/travis/feross/multistream/master.svg
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[travis-url]: https://travis-ci.org/feross/multistream
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[npm-image]: https://img.shields.io/npm/v/multistream.svg
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[npm-url]: https://npmjs.org/package/multistream
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[downloads-image]: https://img.shields.io/npm/dm/multistream.svg
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[downloads-url]: https://npmjs.org/package/multistream
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[standard-image]: https://img.shields.io/badge/code_style-standard-brightgreen.svg
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[standard-url]: https://standardjs.com
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#### A stream that emits multiple other streams one after another (streams3)
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[](https://saucelabs.com/u/multistream)
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Simple, robust streams3 version of [combined-stream](https://www.npmjs.org/package/combined-stream). Allows you to combine multiple streams into a single stream. When the first stream ends, the next one starts, and so on, until all streams are consumed.
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This module is used by [WebTorrent](http://webtorrent.io), specifically [create-torrent](https://github.com/feross/create-torrent).
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### install
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```
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npm install multistream
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```
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### usage
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Use `multistream` like this:
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```js
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var MultiStream = require('multistream')
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var fs = require('fs')
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var streams = [
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fs.createReadStream(__dirname + '/numbers/1.txt'),
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fs.createReadStream(__dirname + '/numbers/2.txt'),
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fs.createReadStream(__dirname + '/numbers/3.txt')
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]
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new MultiStream(streams).pipe(process.stdout) // => 123
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```
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You can also create an object-mode stream with `MultiStream.obj(streams)`.
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To lazily create the streams, wrap them in a function:
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```js
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var streams = [
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fs.createReadStream(__dirname + '/numbers/1.txt'),
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function () { // will be executed when the stream is active
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return fs.createReadStream(__dirname + '/numbers/2.txt')
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},
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function () { // same
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return fs.createReadStream(__dirname + '/numbers/3.txt')
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}
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]
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new MultiStream(streams).pipe(process.stdout) // => 123
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```
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Alternatively, streams may be created by an asynchronous "factory" function:
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```js
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var count = 0;
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function factory (cb) {
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if (count > 3) return cb(null, null)
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count++
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setTimeout(function () {
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cb(null, fs.createReadStream(__dirname + '/numbers/' + count + '.txt'))
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}, 100)
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}
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new MultiStream(factory).pipe(process.stdout) // => 123
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```
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### contributors
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- [Feross Aboukhadijeh](http://feross.org)
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- [Mathias Buus](https://github.com/mafintosh/)
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- [Yuri Astrakhan](https://github.com/nyurik/)
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### license
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MIT. Copyright (c) [Feross Aboukhadijeh](http://feross.org).
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