How to take user input in nodejs using process.stdin for Hackerearth code

Question

I am writing nodejs code for Hackerearth test. I am pressing enter key but the process.stdin.on('end',function(){}) is not getting called. So I want to know when this 'end' event will get called? Or Can I use any other library for user input on Hackerearth. I have also views multiple question on stackoverflow for same but didn't get answer.

process.stdin.resume();

process.stdin.setEncoding("utf-8");

var input = '';

process.stdin.on("data", function (n) {

input += n;

});



 process.stdin.on("end",function(){

   console.log(input)

 })

end is called either when you close stdin (for example if you do node myscript.js < foo.txt and you've reached the last byte of the text file) or when you send the end-of-file character (usually by pressing ctrl-D) — slebetman
– slebetman, Commented Sep 5, 2019 at 5:41
But here I am not reading any file. Just taking user input. Even on pressing ctrl + D it's still not calling 'end ' event. — Shubham J.
– Shubham J., Commented Sep 5, 2019 at 5:54

Michael Dreher · Accepted Answer · 2019-09-05 06:52:47Z

2

The callback of process.stdin.on("data" is called when a 'return' is pressed (EOL=end of line) and you will get the text of the entered line.

The callback of process.stdin.on("end" is called when the end of input (EOF=end of file) is reached. For an interactive console this is when you press ^D under Linux/MacOS (ctrl-D : 'ctrl'-key + 'D'-key). I think on Windows this might need to press ^Z (ctrl-Z) instead of ^D.

Depending on your needs, you have to use the "data" event handler to do your work instead of using the "end" event handler. What is the criteria to start your input processing? When it is not the reading of EOF or EOL, then you need to check that criteria in the "data" handler.

After EOL has been read, the script automatically ends. It is unclear to me if this is what you want.

answered Sep 5, 2019 at 6:52

Michael Dreher

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Comments

roni.radev · Accepted Answer · 2019-09-05 22:07:41Z

The end event is called when Node.js process is about to exit. Usually, you would expect this to happen when you press CRL+C or CRL+D. But CRL+C interrupts the process, so Node can't print anything in the console no more. If you are on Windows machine CRL+D is not supported by the interface so nothing will happen. See the issue here

So what you can do is to use the readline module. The close event will be triggered when you press either CRL+D or CRL+C.

const readline = require('readline');

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});

let input = '';

rl.on('line', (inputString) => {
    input += inputString;
});

rl.on('close', () => {
    console.log(input);
});

Shivam Kumar · Accepted Answer · 2025-03-21 12:48:50Z

0

You can do something like this for multi-line input and exit anywhere you want.

process.stdin.setEncoding('utf-8');
let count=0,arr=[];
process.stdin.on("data", (chunk) => {
    count+=1;
    arr.push(chunk.split(" ").map(Number));
    if(count>1){
        console.log(arr);
        //call function here
        process.exit(0);
    }
});

answered Mar 21 at 12:48

Shivam Kumar

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