将多维数组扁平化为一维数组

1.递归

function flattenArray(arr) {
  let result = [];

  for (let i = 0; i < arr.length; i++) {
    if (Array.isArray(arr[i])) {
      result = result.concat(flattenArray(arr[i]));
    } else {
      result.push(arr[i]);
    }
  }

  return result;
}

// 示例
const array = [1, [2, 3], [4, [5, 6]]];
const newArray = flattenArray(array);
console.log(newArray); // 输出： [1, 2, 3, 4, 5, 6]

2. ES6的方法flat

const array = [1, [2, 3], [4, [5, 6]]];
const newArray = array.flat(Infinity);
console.log(newArray); // 输出： [1, 2, 3, 4, 5, 6]

3. 数组reduce方法

const array = [1,9,[1, 2], [3, [4, 5]], 6];
const newArray = array.reduce((acc, curr) => acc.concat(curr), []);
console.log(newArray); // 输出 [1,9,1,2,3,4,5,6]