Challenge #1

houses.json

[
  { "name": "Atreides", "planets": "Calladan" },
  { "name": "Corrino", "planets": ["Kaitan", "Salusa Secundus"] },
  { "name": "Harkonnen", "planets": ["Giedi Prime", "Arrakis"] }
]

interfaces.ts

interface House {
...
}

interface HouseWithID {
...
}

function findHouses(houses: string): HouseWithID[];
function findHouses(
  houses: string,
  filter: (house: House) => boolean
): HouseWithID[];
function findHouses(houses: House[]): HouseWithID[];
function findHouses(
  houses: House[],
  filter: (house: House) => boolean
): HouseWithID[];

console.log(
  findHouses(JSON.stringify(houses), ({ name }) => name === "Atreides")
);

console.log(findHouses(houses, ({ name }) => name === "Harkonnen"));

Here's an easy to understand solution

  { name: "Atreides", planets: "Calladan" },
  { name: "Corrino", planets: ["Kaitan", "Salusa Secundus"] },
  { name: "Harkonnen", planets: ["Giedi Prime", "Arrakis"] },
];

interface House {
  name: string;
  planets: string | string[];
}

interface HouseWithID {
  name: string;
  planets: string | string[];
  id: number;
}

function findHouses(houses: string): HouseWithID[];

function findHouses(
  houses: string,
  filter: (house: House) => boolean
): HouseWithID[];
function findHouses(houses: House[]): HouseWithID[];

function findHouses(
  houses: House[],
  filter: (house: House) => boolean
): HouseWithID[];

function findHouses(
  input: string | House[],
  filter?: (house: House) => Boolean
) {
  const temp = (
    typeof input === "string" ? JSON.parse(input) : input
  ) as House[];
  let filteredHouses = filter ? temp.filter(filter) : temp;

  return filteredHouses.map(
    (house, id): HouseWithID => ({
      ...house,
      id,
    })
  );
}

console.log(
  findHouses(JSON.stringify(houses), ({ name }) => name === "Atreides")
);

console.log(findHouses(houses, ({ name }) => name === "Harkonnen"));

in the tsconfig.json file you can enable "resolveJsonModule": true, so you can import the json file as import housesData from "./data/houses.json"; that way is an array

interface House {
	name: string;
	planets: string | string[];
}
const houses: House[] = [
	{ name: "Atreides", planets: "Calladan" },
	{ name: "Corrino", planets: ["Kaitan", "Salusa Secundus"] },
	{ name: "Harkonnen", planets: ["Giedi Prime", "Arrakis"] },
];

interface HouseWithID extends House {
	id: number;
}

type FilterFunction = (houses: House) => boolean;

function addHouseId(houses: House[]): HouseWithID[] {
	return houses.map((house, index) => {
		const newHouse: HouseWithID = { ...house, id: index };
		return newHouse;
	});
}
function findHouses(houses: string): HouseWithID[];
function findHouses(houses: string, filter: FilterFunction): HouseWithID[];
function findHouses(houses: House[]): HouseWithID[];
function findHouses(houses: House[], filter: FilterFunction): HouseWithID[];

function findHouses(arg1: unknown, arg2?: FilterFunction): HouseWithID[] {
	if (typeof arg1 === "string") arg1 = JSON.parse(arg1);
	if (arg2) {
		return addHouseId(arg1 as House[]).filter((house) => arg2(house));
	} else {
		return addHouseId(arg1 as House[]);
	}
}

console.log(
	findHouses(JSON.stringify(houses), ({ name }) => name === "Atreides")
);

console.log(findHouses(houses, ({ name }) => name === "Harkonnen"));

Hi @jherr ,

Thanks for your series.

Here's my solution :

import data from "./houses.json";

interface House {
    name: string;
    planets: string[];
 }
    
interface HouseWithID {
    Id: number;
    House: House;
}

function findHouses(houses: string): HouseWithID[];
function findHouses(houses: string, filter?: (house: House) => boolean): HouseWithID[];
function findHouses(houses: House[]): HouseWithID[];
function findHouses(houses: House[], filter?: (house: House) => boolean): HouseWithID[];
function findHouses(houses: unknown, filter?: (house: House) => boolean): HouseWithID[] {
    let housesWithId: HouseWithID[] = [];
    var i = 1;

    let houseArray = (typeof houses === `string` ? JSON.parse((houses as string)) : houses) as House[]; 

    houseArray.map(h => {
        if(filter?.(h))
            housesWithId.push({Id: i, House: h});
        i++;
    });
    
    return housesWithId;
}

console.log(
  findHouses(JSON.stringify(data), ({ name }) => name === "Atreides")
);

console.log(findHouses(data as any, ({ name }) => name === "Harkonnen"));

import houses from "./houses.json";

interface House {
  name: string;
  planets: string | string[];
}

interface HouseWithID {
  id: number;
  house: House;
}

type FilterFunc = (house: House) => boolean;

function findHouses(houses: string): HouseWithID[];
function findHouses(houses: string, filter: FilterFunc): HouseWithID[];
function findHouses(houses: House[]): HouseWithID[];
function findHouses(houses: House[], filter: FilterFunc): HouseWithID[];

function findHouses(houses: unknown, filter?: unknown): HouseWithID[] {
  let housesWithID: HouseWithID[] = (
    typeof houses === "string" ? JSON.parse(houses) : houses
  ).map((house: House, index: number) => ({
    house,
    id: index + 1,
  }));

  if (typeof filter === "function") {
    housesWithID = housesWithID.filter((house: HouseWithID) =>
      (filter as FilterFunc)(house.house)
    );
  }

  return housesWithID;
}

console.log(findHouses(JSON.stringify(houses)));

console.log(
  findHouses(JSON.stringify(houses), ({ name }) => name === "Atreides")
);

console.log(findHouses(houses, ({ name }) => name === "Harkonnen"));