扁平化多维数组

function fn(array, result = []) {
    for (let i of array) {
        if (Array.isArray(i)) {
            fn(i, result)
        } else {
            result.push(i)
        }
    }
    return result
}
let s = fn([1, 2, 3, [1, 2, 2, 3, [4, 5, 6]]])
console.log([...new Set(s)]);