How do I recursively use the reduce () method in javascript?

Question

The question is to use reduce () to work with an array of arrays and return a homogeneous array without sub-arrays. For example, [1,2, [3, [4,5]]] will return [1,2,3,4,5].

Here is the code that works, given that the sub-array itself is not another array of arrays -

var a = [3,[4,[5,[6,7]]]];
var b = 8;
var c = [9,10];
var x = []

var arr = [1,2,a,b,c];
arr = [1,2,3,4,c];

console.log(arr.reduce(function oneArray(a,b)
    {
        return a.concat(b); 
    },x))

Please note that I am changing my arr array since the code does not work for the first arr array ie [1,2, a, b, c]. For arr [1,2,3,4, c] the returned object is [1,2,3,4,9,10]

Here is my attempt to make it work for the first arr

function oneArray(a,b)
    {
        if (typeof b == "object")
            b = b.reduce(oneArray(x,y),[]);
        return a.concat(b); 
    }

    console.log(arr.reduce(oneArray(a,b),x));

It gives me an error

Uncaught TypeError: [object Array] is not a function (anonymous function) @ Flattening.html: 27

It interprets my oneArray function as an array, not a function

, , ( ) , . - , [1,2,3,4,5,6,78,9,10], (), -?

Answer 1

.

: .

function flat(r, a) {
    if (Array.isArray(a)) {
        return a.reduce(flat, r);
    }
    r.push(a);
    return r;
}

var array = [3, [4, [5, [6, 7]]]];
document.write('<pre>' + JSON.stringify(array.reduce(flat, []), 0, 4) + '</pre>');

Hide result