const data = [1, 2, 3, 4, 5];

const initialObject = {};

const reducer = data.reduce(
  (acc, value) => {
    acc[value] = value * 2;
    return acc;
  },
  initialObject
);

console.log(reducer);

//output
initialObject {1: 2, 2: 4, 3: 6, 4: 8, 5: 10}