Module: through

Methods

<static> buf(transform, flush) → {Transform}

It is a conveniece method for through({objectMode: false}, transformFn, flushFn);
If called without arguments, returns a passthrough Transform

Parameters:

Name	Type	Argument	Description
transform	function	<optional>	_transform function as described here
flush	function	<optional>	_flush function as described here (same link as above)

Source:

• index.js, line 222

Returns:

A instance of Transform stream from readable-stream@1.0.x

Type

Transform

Example

// see the factory method.
var thr = through.factory({objectMode: true});
var myData = new Buffer('my data');
var streamBuf = thr.buf(function(chunk, enc, done){
  expect(chunk).to.be.equal(myData);
  expect(chunk).to.not.be.equal('my data');
  done();
});
streamBuf.write(myData);

<static> ctor(options, transform, flush) → {Transform}

Note: This is the same ctor method from through2
If called without arguments, returns a passthrough Transform

Parameters:

Name	Type	Argument	Description
options	Object	<optional>	Same options as seen here
transform	function	<optional>	_transform function as described here
flush	function	<optional>	_flush function as described here (same link as above)

Source:

• index.js, line 153

Returns:

A pre-configured Transform contructor from readable-stream@1.0.x

Type

Transform

Example

var Transform = require('readable-stream').Transform;
var Ctor = through.ctor({objectMode: true}, transformFn, flushFn);
var streamA = new Ctor();

// no need for the new operator
var streamB = Ctor(); 

//overriding options
var streamC = Ctor({objectMode: false}); 

expect(streamA).to.be.an.instanceof(Transform);
expect(streamB).to.be.an.instanceof(Transform);
expect(streamC).to.be.an.instanceof(Transform);

<static> factory(options) → {through}

A factory method for creating a custom through instance.

Parameters:

Name	Type	Argument	Description
options	Object	<optional>	Object passed to stream.Transfrom constructor as described here and here Properties Name Type Argument Default Description highWaterMark Number <optional> 16kb The maximum number of bytes to store in the internal buffer before ceasing to read from the underlying resource. encoding String <optional> <nullable> null If specified, then buffers will be decoded to strings using the specified encoding. objectMode Boolean <optional> false Whether this stream should behave as a stream of objects. Meaning that stream.read(n) returns a single value instead of a Buffer of size n. allowHalfOpen Boolean <optional> true If set to false, then the stream will automatically end the readable side when the writable side ends and vice versa.

Source:

• index.js, line 272

Returns:

A through function with options pre-configured as default

Type

through

Example

var thrObj = through.factory({objectMode: true});

var streamObj = thrObj(function(string, enc, done){
  expect(string).to.be.equal('my data');
  done();
});
streamObj.write('my data');



var myData = new Buffer('my data');
var thrBuf = through.factory({objectMode: false, highWaterMark: 1000*Math.pow(2,6)});

var streamBuf = thrBuf(function(chunk, enc, done){
  expect(chunk).to.be.equal(myData);
  expect(chunk).to.not.be.equal('my data');
  done();
});
streamBuf.write(myData);

<static> obj(transform, flush) → {Transform}

It is a conveniece method for through({objectMode: true}, transformFn, flushFn);
If called without arguments, returns a passthrough Transform

Note: This is the same obj method from through2

Parameters:

Name	Type	Argument	Description
transform	function	<optional>	_transform function as described here
flush	function	<optional>	_flush function as described here (same link as above)

Source:

• index.js, line 186

Returns:

A instance of Transform stream from readable-stream@1.0.x

Type

Transform

Example

var stream = through.obj(function(string, enc, done){
  expect(string).to.be.deep.equal({data: 'myData'});
  done();
});
stream.write({data: 'myData'});

through(options, transform, flush) → {Transform}

Parameters:

Name	Type	Argument	Description
options	Object	<optional>	Same options as seen here
transform	function	<optional>	_transform function as described here
flush	function	<optional>	_flush function as described here (same link as above)

Source:

• index.js, line 100

Returns:

A instance of Transform stream from readable-stream@1.0.x

Type

Transform

Examples

var expect = require('chai').expect;
var through = require("super-stream.through")

var streamA = through.obj(function(counter, enc, done){
  counter += 1;
  done(null, counter);
});
var streamB = through({objectMode: true}, function(counter, enc, done){
  counter += 1;
  done(null, counter);
});

thr = through.factory({objectMode: true});

streamA.pipe(streamB).pipe(thr(function(counter, enc, done){
  expect(counter).to.be.equal(2);
}));

streamA.write(0);

var streamA = through(function(chunk, enc, done){
  data = chunk.toString();
  done(null, new Buffer(data +'-'+ data));
});

thrObj = through.factory({objectMode: true});
var streamB = thrObj.buf(function(chunk, enc, done){
  expect(chunk.toString()).to.be.equal('myData-myData');
  done();
});
 
streamA.pipe(streamB);
streamA.write(new Buffer('myData'));