Node.js Stream readable.pipe() Method

The readable.pipe() method in a Readable Stream is used to attach a Writable stream to the readable stream so that it consequently switches into flowing mode and then pushes all the data that it has to the attached Writable. 

Syntax:

readable.pipe( destination, options )

Parameters: This method accept two parameters as mentioned above and described below:

• destination: This parameter holds the destination of writing data.
• options: This parameter holds the pipe options.

Return Value: It returns the stream.Writable destination, allowing for a chain of pipes if it is a Duplex or a Transform stream. Below examples illustrate the use of readable.pipe() method in Node.js: 

Example 1:

javascript

// Node.js program to demonstrate the
// readable.pipe() method

// Accessing fs module
var fs = require("fs");

// Create a readable stream
var readable = fs.createReadStream('input.txt');

// Create a writable stream
var writable = fs.createWriteStream('output.txt');

// Calling pipe method
readable.pipe(writable);

console.log("Program Ended");

Output:

Program Ended

So, after the piping method the file named “output.text” must contain the data that was in the file “input.text”. 

Example 2:

javascript

// Node.js program to demonstrate
// the chaining of streams using
// readable.pipe() method

// Accessing fs and zlib module
var fs = require("fs");
var zlib = require('zlib');

// Compress the file input.text to
// input.txt.gz using pipe() method
fs.createReadStream('input.text')
   .pipe(zlib.createGzip())
   .pipe(fs.createWriteStream('input.text.gz'));

console.log("File Compressed.");

Output:

File Compressed.

Reference: https://nodejs.org/api/stream.html#stream_readable_pipe_destination_options.