Write a JavaScript program to return the minimum-maximum value of an array, after applying the provided function to set comparing rule

const reduce_Which = (arr, comparator = (a, b) => a - b) =>
  arr.reduce((a, b) => (comparator(a, b) >= 0 ? b : a));
console.log(reduce_Which([1, 3, 2])); 
console.log(reduce_Which([10, 30, 20], (a, b) => b - a));  
console.log(reduce_Which(
  [{ name: 'Kevin', age: 16 }, { name: 'John', age: 20 }, { name: 'Ani', age: 19 }],
  (a, b) => a.age - b.age));