undefined. I can't understand?

Question

var name = prompt("Write your name: ");
var age = prompt("type your age: ");
function FucGetDate(){
var person = [];
person[name];
person[age];
document.write(person[age])
}
FucGetDate()

Answer 1

You have not assigned the name and age variables to your person array.
Maybe you meant something like:
person['name'] = name;
person['age'] = age;

Answer 2

James is correct you need to assign the values of age and name to your array

Answer 3

person[0]=name;
person [1]=age;