https://github.com/tilfin/promised-lifestream

Creating promisified stream pipeline for Node.js
https://github.com/tilfin/promised-lifestream

nodejs npm-module promise stream

Last synced: 3 months ago
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Creating promisified stream pipeline for Node.js

• Host: GitHub
• URL: https://github.com/tilfin/promised-lifestream
• Owner: tilfin
• License: mit
• Created: 2016-09-19T04:37:17.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2018-11-28T13:13:58.000Z (about 6 years ago)
• Last Synced: 2024-10-05T06:55:42.200Z (4 months ago)
• Topics: nodejs, npm-module, promise, stream
• Language: JavaScript
• Homepage:
• Size: 11.7 KB
• Stars: 6
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
Promised Lifestream

===================

[![NPM Version][npm-image]][npm-url]

[![Build Status](https://travis-ci.org/tilfin/promised-lifestream.svg?branch=master)](https://travis-ci.org/tilfin/promised-lifestream)

[![Coverage Status](https://coveralls.io/repos/github/tilfin/promised-lifestream/badge.svg?branch=master)](https://coveralls.io/github/tilfin/promised-lifestream?branch=master)

[![dependencies Status](https://david-dm.org/tilfin/promised-lifestream/status.svg)](https://david-dm.org/tilfin/promised-lifestream)

Creating promisified stream pipeline for Node.js

## Feature

* Streams are pipelined and it resolves when last stream have finished.

* If an error occurred at any stream, it rejects with the error.

* If last stream is Readable or Transform, it appends auto-generated writer to streams.

* Last stream must raise `finish` event. `process.stdout` doesn't raise it.

## Install

```

$ npm install -save promised-lifestream

```

## How to use

**PromisedLifestream(streams, [options])**

* `streams` `>` streams composes pipeline. The first stream must be Readable. The second and any later stream must be Writable. The last stream can be Transform.

* `options` ``

  * `needResult` `` Whether the last stream result is resolved or not. Defaults to false

## Example

```javascript

'use strict';

const fs = require('fs');

const stream = require('stream');

const es = require('event-stream');

const PromisedLifestream = require('promised-lifestream');

var i = 0;

PromisedLifestream([

  new stream.Readable({

    read(size) {

      if (++i < 10) {

        this.push(String(i));

      } else {

        this.push(null);

      }

    }

  }),

  new stream.PassThrough(),

  fs.createWriteStream('out.txt')

])

.then(() => {

  const str = fs.readFileSync('out.txt', { encoding: 'ascii' });

  console.log(str);

  // 123456789

})

.catch(err => {

  console.error(err);

});

```

### Get last result

```javascript

PromisedLifestream([

  es.readArray([1, 2, 3]),

  es.map(function (data, callback) {

    callback(null, data * 2);

  })

], {

  needResult: true

})

.then(result => {

  console.log(result);

  // [2, 4, 6]

})

.catch(err => {

  console.error(err);

});

```

## License

  [MIT](LICENSE)

[npm-image]: https://img.shields.io/npm/v/promised-lifestream.svg

[npm-url]: https://npmjs.org/package/promised-lifestream