JavaScript -查找所有组合，包括单独组合和双重组合？

function getCombinations(arr, n) {
  const result = [];
  const indices = Array.from({ length: n }, (_, i) => i);

  function helper(current) {
    if (current.length === n) {
      result.push(current.map(i => arr[i]));
      return;
    }

    for (let i = indices[current.length]; i < arr.length; i++) {
      const newIndices = indices.slice();
      newIndices[current.length] = i;
      helper(newIndices);
    }
  }

  helper([]);
  return result;
}

const arr = [1, 2, 3, 4];
const singleCombinations = getCombinations(arr, 1);
const doubleCombinations = getCombinations(arr, 2);

console.log("单独组合:", singleCombinations);
console.log("双重组合:", doubleCombinations);

const uniqueArr = Array.from(new Set(arr));
const combinations = getCombinations(uniqueArr, n);