Node.js Stream readable.readableLength Property

The readable.readableLength property in a readable Stream that is used to check the number of bytes in the queue which is ready to be read.

Syntax:

readable.readableLength

Return Values: It returns the number of bytes in the queue which are ready to be read.

Below examples illustrate the use of readable.readableLength property in Node.js:

Example 1:

// Node.js program to demonstrate the
// readable.readableLength Property

// Accessing stream module
const stream = require('stream');

// Creating a Readable stream
const readable = new stream.Readable("input.txt");

// Calling readable.readableLength
// Property
readable.readableLength;

Output:

0

Example 2:

// Node.js program to demonstrate the
// readable.readableLength property

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

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

// Instructions for reading data
readable.on('readable', () => {
  let chunk;

  // Using while loop and calling
  // read method
  while (null !== (chunk = readable.read())) {

    // Displaying the chunk length
    console.log(`read: ${chunk.length}`);
     }
});

// Calling readableLength property
readable.readableLength;

Output:

0
read: 13

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