Remove duplicates from an array

Write a function removeDuplicates(values) that returns a new array without duplicates: every value stays once.

• values is an array of numbers and strings. One array can hold both.
• Keep the first occurrence of every value, in the original order: [3, 1, 3, 2, 1] gives [3, 1, 2]. Do not sort the result.
• Two values are the same only when they are strictly equal (===): 1 and '1' are different, 'a' and 'A' are different.
• An empty array gives [].
• Return a new array, also when there are no duplicates. Do not change (mutate) the input array.

The interviewer asked you not to use Map or Set. The tests check only the result; keep to the rule yourself. The array method includes can tell you if a value is already in the result.