A solution for https://buttondown.com/cassidoo/archive/your-voice-matters-your-stories-are-worth-telling/

_README.md

Prerequisite: Deno v2

deno run https://gist.github.com/jihchi/9cac764592a0d59d9dde89a1bf88f0a2/raw/solve.ts

solve.ts

function knightMoves(coord: [number, number]): [number, number][] {
    const up = [-1, 0];
    const down = [1, 0];
    const left = [0, -1];
    const right = [0, 1];

    const moves = [
      [up, up, left],
      [up, up, right],
      [right, right, up],
      [right, right, down],
      [down, down, left],
      [down, down, right],
      [left, left, up],
      [left, left, down],
    ];

    return moves
      .map((moves) =>
        moves.reduce<[number, number]>(
          (acc, move) => [acc[0] + move[0], acc[1] + move[1]],
          coord,
        )
      )
      .filter((coord) => coord[0] >= 0 && coord[1] < 8);
}

console.log(knightMoves([4, 4]));
// output:
// [
//   [2, 3],
//   [2, 5],
//   [3, 2],
//   [3, 6],
//   [5, 2],
//   [5, 6],
//   [6, 3],
//   [6, 5],
// ]

console.log(knightMoves([0, 0]));
// output:
// [
//   [1, 2],
//   [2, 1],
// ]

console.log(knightMoves([1, 2]));
// output: 
// [
//   [0, 0],
//   [0, 4],
//   [2, 0],
//   [2, 4],
//   [3, 1],
//   [3, 3],
// ]