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https://github.com/jahewson/node-byline

Line-by-line Stream reader for node.js
https://github.com/jahewson/node-byline

Last synced: 21 days ago
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Line-by-line Stream reader for node.js

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# byline — buffered stream for reading lines



![npm package](https://nodei.co/npm/byline.png?downloads=true&downloadRank=true)



`byline` is a simple module providing a `LineStream`.



- node v0.10 `streams2` (transform stream)

- supports `pipe`

- supports both UNIX and Windows line endings

- supports [Unicode UTS #18 line boundaries](http://www.unicode.org/reports/tr18/#Line_Boundaries)

- can wrap any readable stream

- can be used as a readable-writable "through-stream" (transform stream)

- super-simple: `stream = byline(stream);`



## Install



    npm install byline



or from source:



    git clone git://github.com/jahewson/node-byline.git

    cd node-byline

    npm link



# Convenience API



The `byline` module can be used as a function to quickly wrap a readable stream:



```javascript

var fs = require('fs'),

    byline = require('byline');



var stream = byline(fs.createReadStream('sample.txt', { encoding: 'utf8' }));

```



The `data` event then emits lines:



```javascript

stream.on('data', function(line) {

  console.log(line);

});

```



# Standard API

    

You just need to add one line to wrap your readable `Stream` with a `LineStream`.



```javascript

var fs = require('fs'),	

    byline = require('byline');



var stream = fs.createReadStream('sample.txt');

stream = byline.createStream(stream);



stream.on('data', function(line) {

  console.log(line);

});

```



# Piping



`byline` supports `pipe` (though it strips the line endings, of course).



```javascript

var stream = fs.createReadStream('sample.txt');

stream = byline.createStream(stream);

stream.pipe(fs.createWriteStream('nolines.txt'));

```



Alternatively, you can create a readable/writable "through-stream" which doesn't wrap any specific

stream:



```javascript

var stream = fs.createReadStream('sample.txt');

stream = byline.createStream(stream);

stream.pipe(fs.createWriteStream('nolines.txt'));

	

var input = fs.createReadStream('LICENSE');

var lineStream = byline.createStream();

input.pipe(lineStream);



var output = fs.createWriteStream('test.txt');

lineStream.pipe(output);

```



# Streams2 API

    

Node v0.10 added a new streams2 API. This allows the stream to be used in non-flowing mode and is

preferred over the legacy pause() and resume() methods.



```javascript

var stream = fs.createReadStream('sample.txt');

stream = byline.createStream(stream);



stream.on('readable', function() {

  var line;

  while (null !== (line = stream.read())) {

    console.log(line);

  }

});

```



# Transform Stream



The `byline` transform stream can be directly manipulated like so:



```javascript

var LineStream = require('byline').LineStream;



var input = fs.createReadStream('sample.txt');

var output = fs.createWriteStream('nolines.txt');



var lineStream = new LineStream();

input.pipe(lineStream);

lineStream.pipe(output);



```



# Empty Lines



By default byline skips empty lines, if you want to keep them, pass the `keepEmptyLines` option in

the call to `byline.createStream(stream, options)` or `byline(stream, options)`.



# Tests



    npm test



# v0.8



If you want to use `node-byline` with node v0.8 then you can use the 2.1.x series. Simply use the

following in your `package.json`:



```javascript

  "dependencies": {

  "byline": ">=2.1.0 <3.0.0"

},

```



# Simple

Unlike other modules (of which there are many), `byline` contains no:



- monkeypatching

- dependencies

- non-standard 'line' events which break `pipe`

- limitations to only file streams

- CoffeeScript

- unnecessary code