memorystream

What is memorystream?

The memorystream npm package is a simple stream implementation that can be used to store data in memory. It is useful for testing or for small data manipulation tasks where you want to use streams but don't need to persist the data to disk or send it over a network.

What are memorystream's main functionalities?

Writable and Readable Stream

This feature allows the memorystream to act both as a writable and readable stream. Data can be written to the stream and then piped elsewhere, such as to stdout, or read directly.

const MemoryStream = require('memorystream');
const memStream = new MemoryStream();
memStream.write('Data to store in memory stream');
memStream.pipe(process.stdout);

Data Capture for Testing

Memorystream can be used to capture output in testing environments. By writing to the stream and then converting it to a string, you can easily assert the output of the stream.

const MemoryStream = require('memorystream');
const memStream = new MemoryStream();
memStream.write('Test data');
memStream.end();
console.log(memStream.toString());

Other packages similar to memorystream

stream-buffers

The 'stream-buffers' npm package offers similar functionality to 'memorystream' by providing in-memory storage for streams. It differs by offering more detailed control over the size and growth of the internal buffer.

memory-streams

Similar to 'memorystream', 'memory-streams' provides classes for readable and writable memory streams. It is often used for testing purposes like 'memorystream', but it provides additional features such as high-water mark management.

README

Introduction

node-memorystream - this module allow create streams in memory. It can be used for emulating file streams, filtering/mutating data between one stream and another, buffering incoming data, being the gap between two data/network streams of variable rates, etc. MemoryStream support read/write states or only read state or only write state. The API is meant to follow node's Stream implementation. Module supports streams for node > 0.10 now.

Original module is here git://github.com/ollym/memstream.git was remade and improved.

Installation

If you have npm installed, you can simply type:

npm install memorystream

Or you can clone this repository using the git command:

git clone git://github.com/JSBizon/node-memorystream.git

Usage

Some examples how to use memorystream module.

Basic I/O Operation

In this example I illustrate the basic I/O operations of the memory stream.

var MemoryStream = require('memorystream');
var memStream = new MemoryStream(['Hello',' ']);

var data = '';
memStream.on('data', function(chunk) {
	data += chunk.toString();
});

memStream.write('World');

memStream.on('end', function() {
	// outputs 'Hello World!'
	console.log(data);
});
memStream.end('!');

Piping

In this example I'm piping all data from the memory stream to the process's stdout stream.

var MemoryStream = require('memorystream');
var memStream = new MemoryStream();
memStream.pipe(process.stdout, { end: false });

memStream.write('Hello World!');

In this example I'm piping all data from the response stream to the memory stream.

var http = require('http'),
	MemoryStream = require('memorystream');

var options = {
	host: 'google.com'
};
var memStream = new MemoryStream(null, {
	readable : false
});

var req = http.get(options, function(res) {
	res.pipe(memStream);
	res.on('end', function() {
		console.log(memStream.toString());
	});
});

Delayed Response

In the example below, we first pause the stream before writing the data to it. The stream is then resumed after 1 second, and the data is written to the console.

var MemoryStream = require('memorystream');

var memStream = new MemoryStream('Hello');
var data = '';
memStream.on('data', function(chunk) {
	data += chunk;
});

memStream.pause();
memStream.write('World!');

setTimeout(function() {
	memStream.resume();
}, 1000);

Documentation

The memory stream adopts all the same methods and events as node's Stream implementation. Documentation is available here.