合并数组javascript中的每3个元素

function mergeEveryThree(arr) {
  return arr.reduce((acc, val, index) => {
    const groupIndex = Math.floor(index / 3);
    if (!acc[groupIndex]) {
      acc[groupIndex] = [];
    }
    acc[groupIndex].push(val);
    return acc;
  }, []);
}

// 示例数组
const array = [1, 2, 3, 4, 5, 6, 7, 8, 9];

// 合并数组中的每3个元素
const mergedArray = mergeEveryThree(array);

console.log(mergedArray);
// 输出: [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

function mergeEveryThree(arr) {
  const remainder = arr.length % 3;
  const paddedArr = remainder ? arr.concat(Array(3 - remainder).fill(null)) : arr;
  return paddedArr.reduce((acc, val, index) => {
    const groupIndex = Math.floor(index / 3);
    if (!acc[groupIndex]) {
      acc[groupIndex] = [];
    }
    acc[groupIndex].push(val);
    return acc;
  }, []);
}

const array = [1, 2, 3, 4, 5, 6, 7, 8];
const mergedArray = mergeEveryThree(array);
console.log(mergedArray);
// 输出: [[1, 2, 3], [4, 5, 6], [7, 8, null]]

function mergeEveryThree(arr) {
  const result = [];
  for (let i = 0; i < arr.length; i += 3) {
    result.push(arr.slice(i, i + 3));
  }
  return result;
}

const array = [1, 2, 3, 4, 5, 6, 7, 8, 9];
const mergedArray = mergeEveryThree(array);
console.log(mergedArray);
// 输出: [[1, 2, 3], [4, 5, 6], [7, 8, 9]]