what is the reason for the output of undefined

Question

the exercise is to make the exit the day of the week
I get that output but it adds undefined
I don't know why it adds undefined, what is the reason?
This is the code:

var year = 2020;
var month = 5;
var day = 12;

console.log(getWeekDay(year, month, day));

function getWeekDay(year, month, day) {
var names = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];
var d = new Date(year, month, day);
//completa la función
console.log(names[d.getDay()])
}

Answer 1

getWeekDay doesn't have a return value. So when you say

console.log(getWeekDay(...))

it logs undefined, since there was no return value from the function.

Either change console.log(names[...]) to return names[...] or just call getWeekDay(...) from main(), not console.log(getWeekDay(...))

Answer 2

Thanks