The concat-stream npm package is a writable stream that concatenates data and calls a callback with the result. It can be used to collect stream data and concatenate it into a single buffer, string, or array. It is useful for collecting stream data from sources like HTTP requests, file reads, and other stream sources.

What are concat-stream's main functionalities?

Concatenate stream data into a buffer

This code sample demonstrates how to use concat-stream to read data from a file and concatenate it into a buffer. The buffer is then converted to a string and logged to the console.

const concat = require('concat-stream');
const fs = require('fs');

const readStream = fs.createReadStream('file.txt');
const concatStream = concat(function(buffer) {
  console.log(buffer.toString());
});

readStream.pipe(concatStream);

Concatenate stream data into a string

This code sample shows how to use concat-stream to collect HTTP response data and concatenate it into a string. The string is then logged to the console.

const concat = require('concat-stream');
const http = require('http');

http.get('http://example.com', function(response) {
  response.pipe(concat(function(data) {
    console.log(data.toString());
  }));
});

Concatenate stream data into an array

This example demonstrates how to use concat-stream to collect data from a readable stream and concatenate it into an array. The resulting array is then logged to the console.

const concat = require('concat-stream');
const { Readable } = require('stream');

const arrayStream = Readable.from(['hello', ' ', 'world']);
const concatStream = concat({ encoding: 'array' }, function(array) {
  console.log(array);
});

arrayStream.pipe(concatStream);

Other packages similar to concat-stream

Readme

Source

concat-stream

Writable stream that concatenates strings or binary data and calls a callback with the result. Not a transform stream -- more of a stream sink.

examples

var concat = require('concat-stream')
var fs = require('fs')
    
var read = fs.createReadStream('readme.md')
var write = concat(function(data) {})
    
read.pipe(write)

works with arrays too!

var write = concat({ encoding: 'array' }, function(data) {})
write.write([1,2,3])
write.write([4,5,6])
write.end()
// data will be [1,2,3,4,5,6] in the above callback

works with buffers too! can't believe the deals!

var write = concat(function(data) {})
write.write(new Buffer('hello '))
write.write(new Buffer('world'))
write.end()
// data will be a buffer that toString()s to 'hello world' in the above callback

or if you want a Uint8Array, you can have those too!

var write = concat({ encoding: 'u8' }, function(data) {})
var a = new Uint8Array(3)
a[0] = 97; a[1] = 98; a[2] = 99
write.write(a)
write.write('!')
write.end(Buffer('!!1'))

methods

var concat = require('concat-stream')

var writable = concat(opts={}, cb)

Return a writable stream that will fire cb(data) with all of the data that was written to the stream. Data can be written to writable as strings, Buffers, arrays of byte integers, and Uint8Arrays.

Use opts.encoding to control what format data should be:

string - get a string
buffer - get back a Buffer (this is the default encoding)
array - get an array of byte integers
uint8array, u8, uint8 - get back a Uint8Array

license

MIT LICENSE

FAQs

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Last updated on 01 Mar 2018

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