Recursive nested array count created by oliverjam - https://repl.it/If1v/0

Recursive nested array count.js

function deepCount(arr) {
  return arr.reduce((acc, item) => {
    acc += 1;
    if (Array.isArray(item)) acc += deepCount(item);
    return acc;
  }, 0);
}

const a = [1, [2, 3, [4, 5, 6]]];

deepCount(a);