FlattenArray - For careers.citrusbyte.com

gistfile1.txt

function flatten(arr) {
  const flat = [].concat(...arr)
  return flat.some(Array.isArray) ? flatten(flat) : flat;
}

/*
  Usage: 
*/
flatten([[1,2,[3]],4])
/*
  Result:
  [1, 2, 3, 4]
*/