@stdlib/streams-node-join

Transform stream which joins streamed data.

Usage no npm install needed!

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README

Join Stream

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Transform stream which joins streamed data.

Installation

npm install @stdlib/streams-node-join

Usage

var joinStream = require( '@stdlib/streams-node-join' );

joinStream( [options] )

Creates a transform stream which joins streamed data.

var stdout = require( '@stdlib/streams-node-stdout' );

var stream = joinStream();

stream.pipe( stdout );

stream.write( '1' );
stream.write( '2' );
stream.write( '3' );

stream.end();

// prints: 1\n2\n3

The function accepts the following options:

  • sep: separator used to join streamed data. Default: '\n'.
  • objectMode: specifies whether a stream should operate in object mode. Default: false.
  • encoding: specifies how Buffer objects should be decoded to strings. Default: null.
  • highWaterMark: specifies the Buffer level at which write() calls start returning false.
  • allowHalfOpen: specifies whether a stream should remain open even if one side ends. Default: false.
  • readableObjectMode: specifies whether the readable side should be in object mode. Default: false.

To set stream options,

var opts = {
    'sep': ',',
    'objectMode': true,
    'encoding': 'utf8',
    'highWaterMark': 64,
    'allowHalfOpen': true,
    'readableObjectMode': false // overridden by `objectMode` option when `objectMode=true`
};

var stream = joinStream( opts );

joinStream.factory( [options] )

Returns a function for creating streams which are identically configured according to provided options.

var opts = {
    'sep': '\t',
    'objectMode': true,
    'encoding': 'utf8',
    'highWaterMark': 64
};

var factory = joinStream.factory( opts );

// Create 10 identically configured streams...
var streams = [];
var i;
for ( i = 0; i < 10; i++ ) {
    streams.push( factory() );
}

This method accepts the same options as joinStream().

joinStream.objectMode( [options] )

This method is a convenience function to create streams which always operate in objectMode.

var stdout = require( '@stdlib/streams-node-stdout' );

var stream = joinStream.objectMode({
    'sep': ','
});

stream.pipe( stdout );

stream.write( 'a' );
stream.write( 'b' );
stream.write( 'c' );

stream.end();

// prints: a,b,c

This method accepts the same options as joinStream(); however, the method will always override the objectMode option in options.

Examples

var splitStream = require( '@stdlib/streams-node-split' );
var inspectStream = require( '@stdlib/streams-node-inspect-sink' );
var joinStream = require( '@stdlib/streams-node-join' );

var inspect;
var split;
var join;
var i;

function log( chunk ) {
    console.log( chunk.toString() );
}

// Create a split stream for tab delimited data:
split = splitStream({
    'sep': /\t/
});

// Create a stream to make newline delimited data:
join = joinStream({
    'sep': '\n'
});

// Create a stream to inspect joined output:
inspect = inspectStream( log );

// Create a stream pipeline:
split
    .pipe( join )
    .pipe( inspect );

// Write values to the split stream...
for ( i = 0; i < 10; i++ ) {
    split.write( i+'\t', 'utf8' );
}
split.end();

See Also

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2022. The Stdlib Authors.