Array flat
// 二维数组平铺 const arr = [11, [22, 33], [44, 55], 66]; const flatArr = [].concat(...arr); //=> [11, 22, 33, 44, 55, 66]// 递归实现 var a = [1, [2, [3, 4, 5]]]; function flatten(arr) { let result = []; for (let i = 0; i < arr.length;
