数组扁平化处理

数组扁平化是指将一个多维数组变为一个一维数组

1. reduce

  const arr = [1, [2, [3, [4, 5]]], 6]
    // => [1, 2, 3, 4, 5, 6]
    // reduce
     const flatten = list => {
         console.log(list)
         return list.reduce((pre, curr) => {
             console.log(pre, curr)
             return pre.concat(isArray(curr) ? flatten(curr) : curr)
         }, [])
     }
     console.log(flatten(arr))

2. 递归

 // 递归
    const res = []
    const flatten = list => {
        for (let index = 0; index < list.length; index++) {
            const element = list[index]
            if (isArray(element)) {
                flatten(element)
            } else {
                res.push(element)
            }
        }
    }
    flatten(arr)
    console.log(res)