Node.js process.stdin Property

The process.stdin property is an inbuilt application programming interface of the process module which listens for the user input. The stdin property of the process object is a Readable Stream. It uses on() function to listen for the event.

Syntax:

process.stdin.on();

Return Value: It doesn’t return any value.

Parameters: This property takes Input from the user.

Below examples illustrate the use of process.stdin property in Node.js:

Example 1: Create a JavaScript file and name this file as index.js.

Javascript

// Node.js program to demonstrate the
// process.stdin Property

// Enter any texts ( User input)
process.stdin.on('data', data => {
  console.log(`You typed ${data.toString()}`);
  process.exit();
});

Run the index.js file using the following command:

node index.js

Output: Now type any text from the terminal, as shown below we have typed GeeksforGeeks

GeeksforGeeks
You typed GeeksforGeeks

Example 2: Create a JavaScript file and name this file as index.js.

Javascript

// Node.js program to demonstrate the
// process.stdin Property

process.stdin.on('readable', () => {
  let chunk;
  // Use a loop to make sure we read all available data.
  while ((chunk = process.stdin.read()) !== null) {
   process.stdout.write(`data: ${chunk}`);
  }
});

Run the index.js file using the following command:

node index.js

Output: Now type any text from the terminal, as shown below we have typed One, followed by Two and so on.

One
data: One
Two
data: Two

Reference: https://nodejs.org/api/process.html#process_process_stdin