SOURCE

// 数组扁平化 去重 排序
const arr = [1, [3, 5, 2], [5, [7, [8, 2]]]]

Array.prototype.myFlat = function() {
    return this.reduce((acc, curr) => {
        return acc.concat(Array.isArray(curr) ? curr.myFlat() : curr)
    }, [])
}

Array.prototype.unique = function() {
    let map = {}
    return this.filter(item => map.hasOwnProperty(item) ? false : (map[item] = true))
}

const sort = (a, b) => a - b

console.log(arr.myFlat().unique().sort(sort))