randomPick.js

// return random intger value: [min, max)
function getRandomInt(min, max) {
  min = Math.ceil(min);
  max = Math.floor(max);
  return Math.floor(Math.random() * (max - min) + min);
}

// return (size m) array picked from 0..<n (n >= m)
// Modified Fisher-Yates Shuffle (derived from <https://qiita.com/hmito/items/9f4bdc8442b6f6b3c7bc>)
function randomPick(n, m) {
  let max = n;
  const map = []
  const ret = []
  for (let i = 0; i < m; i++) {
    let val = getRandomInt(0, max);

    let maxval;
    if (map[max-1] !== undefined) {
      maxval = map[max-1];
    } else if (val !== max-1) {
      maxval = max-1;
    }

    if (map[val] !== undefined) {
      ret[i] = map[val];
    } else {
      ret[i] = val;
    }
    map[val] = maxval;

    max--;
  }
  return ret;
}

// sample
for (let i = 0; i < 10; i++) {
  console.log(randomPick(5, 4));
}

randomPick2.js

const randomPick = (n: number, m: number): number[] => {
    const arr: number[] = [];

    for (let i = 0; i < m; i++) {
        const max = n - 1 - i;
        const picked = Math.floor(Math.random() * (max + 1));

        [arr[picked], arr[max]] = [arr[max] ?? max + 1, arr[picked] ?? picked + 1];
    }

    return arr.slice(n - m, n);
}

for (let i = 0; i < 10; i++) {
    console.log(randomPick(100000,5));
}

See: https://twitter.com/aoki_taichi/status/1366196445787815942?s=20