i399exlang/ex5.js

'use strict';


function factorial(n, callback) {
    if (n < 0) {
        throw 'illegal argument'
    }

    var result = 1;
    while (n > 0) {
        result *= n;
        n--;
    }

    callback(result);
}

factorial(4, res => console.log(`Result: ${res}`))