What is concat-stream?
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
bl
The 'bl' (Buffer List) package is similar to concat-stream as it provides a storage object for collections of Node.js Buffers. It can be used to collect buffers and access them with a standard readable Buffer interface. It differs in its API and additional features like the ability to access data at specific indices without creating a new Buffer.
stream-buffers
The 'stream-buffers' package offers writable and readable stream implementations using a growable buffer. It is similar to concat-stream in that it allows for the collection of stream data, but it also provides more control over the buffer size and growth.
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()
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()
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