Node.js Stream writable.writableLength Property

The writable.writableLength property is an inbuilt application of stream module which is used to check the number of bytes in the queue that is ready to be written. 

Syntax:

writable.writableLength

Return Value: This property returns the number of bytes that is ready to write into the queue. 

Below examples illustrate the use of writable.writableLength property in Node.js: 

Example 1:

javascript

// Node.js program to demonstrate the
// writable.writableLength Property

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

// Creating a stream and creating
// a write function
const writable = new stream.Writable({

  // Write function with its
  // parameters
  write: function(chunk, encoding, next) {

    // Converting the chunk of
    // data to string
    console.log(chunk.toString());
    next();
  }
});

// Calling cork() function
writable.cork();

 //Writing data
writable.write('hi');

// Again writing some data
writable.write('GFG');

// Calling writable.writableLength
// Property
console.log(writable.writableLength);

Output:

5

Example 2:

javascript

// Node.js program to demonstrate the
// writable.writableLength Property

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

// Creating a stream and creating
// a write function
const writable = new stream.Writable({

  // Write function with its
  // parameters
  write: function(chunk, encoding, next) {

    // Converting the chunk of
    // data to string
    console.log(chunk.toString());
    next();
  }
});

// Calling cork() function
writable.cork();

 //Writing data
writable.write('hi');

// Calling uncork() function
writable.uncork();

// Again calling cork function
writable.cork();

// Again writing some data
writable.write('GFG');

// Calling writable.writableLength
// Property
console.log(writable.writableLength);

Output:

hi
3

Here, the data ‘hi’ is not present in buffer anymore So, the buffer has only 3 bytes present data ‘GFG’ takes 3 bytes. 

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