class DataStore {
  constructor(values) {
    this.values = values;
  }
  forEachData(callback) {
    // the callback is invoked with items specific to the logic of DataStore
    callback(0);
    callback(1);
    for (const x of this.values) {
      callback(x);
    }
    for (const x of this.values) {
      callback(2 * x);
    }
  }
}

// Inside my function
const data_store = ...; // DataStore object
const aggregate_op = (accumulator, current_value) => Math.min(accumulator, f(current_value));

// I'm wondering if there is a built-in language or library feature that does this kind of reduction:
let answer = 0;
data_store.forEachData(x => {
  answer = aggregate_op(answer, x);
});

const arr = ...;
let answer = 0;
arr.forEach(x => {
  arr = aggregate_op(arr, x);
});