Node.js Writable Stream pipe Event

Last Updated : 28 Apr, 2025

The pipe event in a Writable Stream is emitted when the stream.pipe() method is being called on a readable stream by attaching this writable to its set of destinations. 

Syntax:

Event: 'pipe'

Return Value: If the pipe() method is being called then this event is emitted else it is not emitted. 

The below examples illustrate the use of the 'pipe' event in Node.js: 

Example 1: 

javascript 
// Node.js program to demonstrate the    
// pipe event

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

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

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

// Handling pipe event
writable.on("pipe", readable => {
    console.log("Piped!");
});

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

console.log("Program Ended.");

Output:

Piped!
Program Ended.

Example 2: 

javascript 
// Node.js program to demonstrate the    
// pipe event

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

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

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

// Handling pipe event
writable.on("pipe", readable => {
    console.log("Piped!");
});

console.log("Program Ended");

Output:

Program Ended

So, here pipe() function is not called so the pipe event is not emitted. 

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

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