Node.js Stream readable.pause() Method

The readable.pause() method is an inbuilt application programming interface of Stream module which is used to stop the flowing mode from emitting ‘data’ events. If any data that becomes accessible will continue to exist in the internal buffer.

Syntax:

readable.pause()

Parameters: This method does not accept any parameters.

Return Value: If this method is used then the reading of data is paused at that time.

Below examples illustrate the use of readable.pause() method in Node.js:

Example 1:

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

// Including fs module
const fs = require('fs');

// Constructing readable stream
const readable = fs.createReadStream("input.txt");
readable.on('data', (chunk) => {
  console.log(`${chunk}`);
});

// Calling pause method
readable.pause();

// Checking if paused or not
readable.isPaused();

Output:

true

Example 2:

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

// Include fs module
const fs = require('fs');

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

// Handling data event
readable.on('data', (chunk) => {
  console.log(`Received ${chunk.length} bytes of data.`);

  // Calling pause method
  readable.pause();

  // After this any data will be displayed
  // after 1 sec.
  console.log('No further data will be displayed for 1 second.');

  // Using setTimeout function
  setTimeout(() => {
    console.log('Now data starts flowing again.');
    readable.resume();
  }, 1000);
});

// Displays that program
// is ended
console.log("Program ends!!");

Output:

Program ends!!
Received 5 bytes of data.
No further data will be displayed for 1 second.
Now data starts flowing again.

However, you can see while running, that after the execution of pause() method, no further data will be displayed for 1 second.

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