js数组递归循环

Question

循环数组

arr = [
   [1, 2],
   [3, 4],
]

输出[13, 14, 23, 34];

循环数组

arr = [
   [1, 2],
   [3, 4],
   [5, 6],
]

输出[135, 136, 145, 146, 235, 236, 245, 246]

循环的数组长度未知，数组的每个子数组长度未知。

要写一个通用的方法？

Answer 1

用数组的reduce方法
let arr = [[1, 2], [3, 4], [5, 6]]
let list = []
arr.reduce((pre, current, index, arr) => {

list = []
for (let i = 0; i < pre.length; i++) {
    for (let j = 0; j < current.length; j++) {
        list.push(+(pre[i] + '' + current[j]))
    }
}
return list

})

console.log(list)