ts-utility

Simple utility functions

Array functions

simpleSort

Sorts an array using supplied functions to get values to sort by. Takes functions returning either strings or numbers.

Somewhat fast. Speed tests using 58mb json (100k entries) sorted by name length and then name descending took around 300ms

Example test case:

it('should sort pokemons on first letter of name and then by weight, descending ', () => {
  const result = simpleSort(
    json.pokemon,
    asc(i => i.name[0]),
    desc(i => Number.parseFloat(i.weight))
  );

  // Below would give the same result.
  // asc|desc functions above actually just returns this type of tuple.
  const result = simpleSort(
    json.pokemon,
    [i => i.name[0], 'asc'],
    [i => Number.parseFloat(i.weight), 'desc']
  );

  expect(result.slice(0, 10).map(i => `${i.name} ${i.weight}`)).toEqual([
    'Arcanine 155.0 kg',
    'Arbok 65.0 kg',
    'Aerodactyl 59.0 kg',
    'Articuno 55.4 kg',
    'Alakazam 48.0 kg',
    'Abra 19.5 kg',
    'Blastoise 85.5 kg',
    'Butterfree 32.0 kg',
    'Beedrill 29.5 kg',
    'Bulbasaur 6.9 kg',
  ]);
});

For more examples see tests

groupBy

A small implemententation of groupBy

type specificGroupNames = 'first' | 'second' | 'third';
const itemsWithSpecificGroups = items as Array<{
  id: number;
  group: specificGroupNames;
}>;

const result = groupBy(itemsWithSpecificGroups, item => item.group);
// result now contains the grouped arrays.
// typescript error occurs if you try to access result.noneexisting since its not in the group names

Other

Deep Partial Set

As the name implies, sets an objects and subobjects properties. Optionally use a function to modify current value.

it('should add 10 gold, 10 silver and 10 copper to persons pouch', () => {
  const person = {
    personal: {
      firstName: 'Test',
      lastName: 'Testsson',
    },
    items: {
      pouch: {color: 'blue', contents: {gold: 10, silver: 20, copper: 30}},
    },
  };

  const result = deepPartialSet(person, {
    items: {
      pouch: {
        contents: {
          gold: i => i + 10,
          silver: i => i + 10,
          copper: i => i + 10,
        },
      },
    },
  });

  expect(result.items.pouch.contents).toEqual({
    gold: 20,
    silver: 30,
    copper: 40,
  });
  // Keep unchanged objects
  expect(result.personal).toBe(person.personal);
  // New objects for the complete tree where a child has a change
  expect(result).not.toBe(person);
  expect(result.items).not.toBe(person.items);
  expect(result.items.pouch).not.toBe(person.items.pouch);
  expect(result.items.pouch.contents).not.toBe(person.items.pouch.contents);
});