Streams

Streams are instances of EventEmitter which can be used to work with streaming data in Node.js
There are mainly four types of the stream:
- Writable:
  - fs.createWriteStream()
- Readable:
  - fs.createReadStream()
- Duplex: (Both Readable and Writable)
  - net.Socket
- Transform: Duplex streams that can modify or transform the data as it is written and read
  - zlib.createDeflate()

Buffers

Buffers is a temporary memory that is mainly used by stream to hold on to some data until consumed.

// Nodejs Buffer
var buf = new Buffer('Hello', 'utf8'); // size is fixed with initial value as Hello
console.log(buf.toString()); // Hello
 
buf.write('wo');
console.log(buf.toString()); // wollo

ES6 has defined ArrayBuffer which is the way of dealing with Buffers in core javascript itself

// ES6 ArrayBuffer
var buffer = new ArrayBuffer(8);
var view = new Int32Array(buffer);
view[0] = 5
view[1] = 15
console.log(view) // Int32Array(2) [ 5, 15 ]

Pipes

Pipes basically combines two streams
Common use case is to read from one stream and write to another stream, copy contents of one file to another for example:

const fs = require('fs');
const readableStream = fs.createReadStream(__dirname + '/input.txt');
const writableStream = fs.createWriteStream(__dirname + '/output.txt');
 
readableStream.pipe(writableStream); // will copy contents of input.txt to output.txt
 
// Alternatively without pipes the code will be the following:
readableStream.on('data', function(chunk) {
	writableStream.write(chunk);
});