Javascript Freecodecamp Algorithm #28: Inventory Update

inventory-update.js

function updateInventory(arr1, arr2) {
  const obj1 = arr1.reduce((acc, [amt, name])=>({
    ...acc,
    [name]: amt
  }), {});
  const obj2 = arr2.reduce((acc, [amt, name])=>({
    ...acc,
    [name]: amt
  }), {});

  for (const name in obj2) {
    if (name in obj1) {
      obj1[name] += obj2[name];
    } else {
      obj1[name] = obj2[name];
    }
  }

  const output = [];
  for (const name in obj1) {
    output.push([obj1[name], name]);
  }

  return output.sort((arr1, arr2) => arr1[1].localeCompare(arr2[1]));
}