I just simply tried to take input using javascript as I started javascript basics, why it's not running?

Question

https://code.sololearn.com/WYtHxTSsZ36R/?ref=app

Answer 1

let x = readLine();
works only in CodeCoach Sololearns compiler which is so created to do this. JavaScript does not have this statement.
Instead you can use prompt() as above mentioned or input tag from HTML.