Node.js Stream readable.unshift() Method

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

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

// Declaring data
var data = '';

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

// Instructions for reading data
readable.on('readable', () => {
  let chunk;
 
  // Using while loop and calling
  // read method
  while (null !== (chunk = readable.read())) {
 
    // Displaying the chunk
    console.log(`read: ${chunk}`);
  }
});
console.log("Program ends!!!");

// Calling unshift method
readable.unshift(data);

// Node.js program to demonstrate the     
// readable.unshift(chunk[, encoding])
// method  

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

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

// Calling setEncoding method
readable.setEncoding('utf8');

// Instructions to unshift data
readable.on("readable", () => {
  let data = readable.read();
  
  while (data === "GfG") {
  
    readable.unshift(data);
    data = readable.read();
  }
  });

// Displays that program 
// is unshifted
  console.log("Unshifted!!");