Node.js Stream writable.writableFinished Property

The writable.writableFinished property is set to true instantly before the emit of the ‘finish’ event.

Syntax:

writable.writableFinished

Return Value: It returns true if ‘finish’ event is called before it else it returns false.
Below examples illustrate the use of writable.writableFinished property in Node.js:

Example 1:

// Node.js program to demonstrate the
// writable.writableFinished 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();
  }
});

// Using for loop and calling
// write method
for (let i = 0; i < 5; i++) {
  writable.write(`GfG, #${i}!`);
}

// Emitting finish event
writable.on('finish', () => {
  console.log('All writes are now complete.');
});

// Calling end function
writable.end('This is the end\n');

// Calling writable.writableFinished
// Property
writable.writableFinished;
writable.destroy();

Output:

GfG, #0!
GfG, #1!
GfG, #2!
GfG, #3!
GfG, #4!
This is the end

All writes are now complete.

Example 2:

// Node.js program to demonstrate the
// writable.writableFinished 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 write() method
writable.write('GfG');

// Calling writable.writableFinished
// Property
writable.writableFinished;
writable.destroy();

Output

GfG

In the above example the output is false as ‘finish’ event is not called before writable.writableFinished property.

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