ice.fo.utils/Array/mergeUnique.js

/**
 * Merge 2 array and remove previous duplicate
 *
 * @param {any[]} a
 * @param {any[]} b
 * @param {(any) => string} indicator
 * @returns
 */
export default function mergeUnique(a, b, indicator = (i) => i.id) {
  const result = [];
  const dict = {};

  a.forEach((i, index) => {
    result.push(i);
    dict[indicator(i)] = index;
  });

  b.forEach((i) => {
    const foundIndex = dict[indicator(i)];
    if (foundIndex != null) {
      result.splice(foundIndex, 1, i);
    } else {
      result.push(i);
    }
  });

  return result;
}