Update Terminal Output Node.js

Question

I've been working on some problems on projecteuler.net, and am programming functions and algorithms to solve these problems in mostly JavaScript (ran in the Node.js environment).

In many of these problems I am going through many thousand different numbers, and I would like to show (in the terminal output) which number it is currently on. I don't want it to just keep writing new lines, but just update the existing line... Is there a way to do this in JavaScript? Possibly with the help of any Node modules?

I know there is a way to clear the console, and so I could just have it clear it and then write the number again, but that would also clear the previous output that I still want to show...

Thanks in advance!

Look into ANSI escape codes if you want to do this by hand, or look into one of the many Node.js libraries. Search keyword is ANSI escape codes — Evert
– Evert, Commented Jul 25, 2021 at 4:10

vsemozhebuty · Accepted Answer · 2021-07-25 15:39:18Z

1

May be this suffices?

import readline from 'readline';

function clearLine() {
  readline.cursorTo(process.stdout, 0);
  readline.clearLine(process.stdout, 0);
}

let counter = 0;

setInterval(() => {
  clearLine();
  process.stdout.write(String(counter++));
}, 1000);

answered Jul 25, 2021 at 15:39

vsemozhebuty

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3 Comments

Jacob Hornbeck Over a year ago

It seems to work how I want it... One question... do you know what the average execution time of that is?

vsemozhebuty Over a year ago

@JacobHornbeck Sorry, I do not(

Jacob Hornbeck Over a year ago

Okay, that's fine. Thank you for your answer, it does help a lot!

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