uniqueArray.ts

function uniqueArray<T>(array: T[], toUniqueValue?: (current: T) => any): T[] {
  const values = toUniqueValue ? array.map(toUniqueValue) : array;
  return array.filter((current, index) => values.indexOf(values[index]) == index);
}
  
// Example
const array = [{ id: 0, k: "a" }, { id: 1, k: "b" }, { id: 2, k: "a" }, { id: 3, k: "c" }];
const result = uniqueArray(array, item => item.k);
expect(result).toEqual([{ id: 0, k: "a" }, { id: 1, k: "b" }, { id: 3, k: "c" }]);