Necesito ayuda con este código

Question

function main() {
var year = parseInt(readLine(), 10);
var month = parseInt(readLine(), 10);
var day = parseInt(readLine(), 10);

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
var days = d.getDay()
switch (days) {
case 0:
console.log(names[0]);
break;
case 1:
console.log(names[1]);
break;
case 2:
console.log(names[2]);
break;
case 3:
console.log(names[3]);
break;
case 4:
console.log(names[4]);
break;
case 5:
console.log(names[5]);
break;
case 6:
console.log(names[6]);
break;
}
}

Answer 1

No ha definido un valor de retorno al final de su función.
o prueba esto

function main(){
variables de entrada
getWeekDay(year, month, day);
}
...