HackerRank Day 1: Functions 10 days of javascript solution

In this Day 1: Functions 10 days of javascript problem you need to Implement a function named factorial that has one parameter: an integer, n. It must return the value of n!.

HackerRank Day 1: Functions problem solution in JavaScript programming.

'use strict';

process.stdin.resume();
process.stdin.setEncoding('utf-8');

let inputString = '';
let currentLine = 0;

process.stdin.on('data', inputStdin => {
    inputString += inputStdin;
});

process.stdin.on('end', _ => {
    inputString = inputString.trim().split('n').map(string => {
        return string.trim();
    });
    
    main();    
});

function readLine() {
    return inputString[currentLine++];
}
/*
 * Create the function factorial here
 */

function factorial(n){
    if(n === 0){
        return 1;
    } else{
        return n * factorial(n-1);
    }
}


function main() {
    const n = +(readLine());
    
    console.log(factorial(n));
}