Node.js Stream readable.destroyed Property

The readable.destroyed property is an inbuilt application programming interface of Stream module which is used to check the readable.destroy() function is being called or not.

Syntax:

readable.destroyed

Return Value: It returns true if readable.destroy() method is being called otherwise returns false.

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

Example 1:

// Node.js program to demonstrate the
// readable.destroyed 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 with parameter
  while (null !== (chunk = readable.read())) {

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

// Handling error event
readable.on('error', err => {
    console.log(err);
});

// Calling destroy method
// with parameter
readable.destroy('error');

// Displays that the stream is
// destroyed
console.log("Stream destroyed");

// Calling readable.destroyed
// Property
readable.destroyed;

Output:

Stream destroyed
true
error

Example 2:

// Node.js program to demonstrate the
// readable.destroyed 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 with parameter
  while (null !== (chunk = readable.read())) {

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

// Displays that the stream is
// destroyed
console.log("Program completed!!");

// Calling readable.destroyed
// Property
readable.destroyed;

Output:

Program completed!!
false
read: hello

So, here readable.destroy() method is not called before readable.destroyed property so it returns false.

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