Simple JavaScript method to return all possible combinations from a given array.

generate-combinations.js

const generateCombinations = (arr, length) => {
  if (length === 0) return [[]];

  if (arr.length === 0 || length > arr.length) return [];

  if (length === 1) return arr.map(item => [item]);

  const combinations = [];

  for (let i = 0; i < arr.length; i++) {
    const withoutCurrent = arr.slice(i + 1);
    const current = arr[i];

    const smallerCombinations = generateCombinations(withoutCurrent, length - 1);
    const combined = smallerCombinations.map(item => [current, ...item]);

    combinations.push(...combined);
  }

  return combinations;
};