javascript 三种数组扁平化方式

1.递归1

let givenArr = [[1, 2, 2], [3, 4, 5, 5], [6, 7, 8, 9, [11, 12, [12, 13, [14]]]], 10];
        // 1.数组扁平化
        function flatten(arr) {
            let res = [];
            for (let i = 0; i < arr.length; i++) {
                if( Array.isArray(arr[i])){
                    res = res.concat(flatten(arr[i]))
                }else{
                    res.push(arr[i])
                }
            }
            return res
        }

console.log(flatten(givenArr))

// [1, 2, 2, 3, 4, 5, 5, 6, 7, 8, 9, 11, 12, 12, 13, 14, 10]

2.递归2

let givenArr = [[1, 2, 2], [3, 4, 5, 5], [6, 7, 8, 9, [11, 12, [12, 13, [14]]]], 10];

function flatten(arr) {
            let res = [];
            res = arr.reduce((total, prev) => {
                return total.concat(Array.isArray(prev) ? flatten(prev) : prev)
            }, [])
            return res;
        }
 console.log(flatten(givenArr))
// [1, 2, 2, 3, 4, 5, 5, 6, 7, 8, 9, 11, 12, 12, 13, 14, 10]

3.flat ECMA 2019 （IE全不兼容 edge 79以后)

let givenArr = [[1, 2, 2], [3, 4, 5, 5], [6, 7, 8, 9, [11, 12, [12, 13, [14]]]], 10];
console.log(givenArr.flat(Infinity))
// [1, 2, 2, 3, 4, 5, 5, 6, 7, 8, 9, 11, 12, 12, 13, 14, 10]