Comparing two objects for additions, deletions, and updates.

update-objects.tsx

const existingFields = [
  {
    id: "1",
    name: "",
    value: "6.2%",
    related_id: "1",
  },
  {
    id: "3",
    name: "",
    value: "5.0%",
    related_id: "1",
  },
  {
    id: "4",
    name: "",
    value: "25",
    related_id: "7",
  },
];

const inputFields = [
  {
    id: "1",
    name: "",
    value: "6.3%",
    related_id: "1",
  },
  {
    id: "3",
    name: "",
    value: "5.0%",
    related_id: "1",
  },
  {
    value: "25",
    related_id: "7",
  },
];

const onlyInLeft = (left, right, compareFunction) =>
  left.filter(
    (leftValue) =>
      !right.some((rightValue) => compareFunction(leftValue, rightValue))
  );

const isSameField = (a, b) => a.id === b.id && a.related_id === b.related_id;

const inBothWithUpdate = (l, r, compareFunction) =>
  l.filter((a) =>
    r.some(
      (b) =>
        compareFunction(a,b)
    )
  );

const isSameFieldButWithUpdatedValues = (a, b) => 
  isSameField(a,b) &&
    (a.name !== b.name || a.value !== b.value);

const onlyInExisting = onlyInLeft(existingFields, inputFields, isSameField);
console.log(`toBeRemoved: ${JSON.stringify(onlyInExisting)}`)

const onlyInInput = onlyInLeft(inputFields, existingFields, isSameField);
console.log(`toBeAdded: ${JSON.stringify(onlyInInput)}`)

const inBothToBeUpdated = inBothWithUpdate(inputFields, existingFields, isSameFieldButWithUpdatedValues)
console.log(`toBeUpdated: ${JSON.stringify(inBothToBeUpdated)}`)