sort-parcels-by-country-curried.js

// given a database of global parcels like this...
const allGlobalParcels = [
  {
    created: 576424800000,
    location: "aus",
    properties: { ... },
  },
  {
    created: 1558163267311,
    location: "us",
    properties: { ... },
  },
  ...2701201201 more items
];

const sortParcelsByCountry = parcels => country => {
  // 1. Filter our list to only include parcels from 'country;
  const countryParcels = parcels.filter(parcel => parcel.location === country);

  // we now return a function that sorts the parcels by date created
  return order => {
    // 2. Sort the list of packages by date
    const sortedResult = [...countryParcels].sort((a, b) => {
      if (order === "ascending") return a.created - b.created;

      // by default return packages by descending order
      return b.created - a.created;
    });

    return sortedResult;
  };
};

// we create a new function with the filtered list of parcels by country in it's closure scope
const sortAusParcelsBy = sortParcelsByCountry(allGlobalParcels)("aus");

const ausParcelsAsc = sortAusParcelsBy("ascending");
const ausParcelsDsc = sortAusParcelsBy("descending");