Bonfire: Steamroller

bonfire-steamroller.js

// Bonfire: Steamroller
// Author: @clive-bunting
// Challenge: http://www.freecodecamp.com/challenges/bonfire-steamroller#
// Learn to Code at Free Code Camp (www.freecodecamp.com)

function steamroller(arr) {
  var flat = [];
  for (var i =0; i < arr.length; i++) {
    if (Array.isArray(arr[i])) {
      var flattened = steamroller(arr[i]);
      flattened.forEach(function(a){flat.push(a);});
    }
    else {
      flat.push(arr[i]);
    }
  }
  return flat;
}

steamroller([1, [2], [3, [[4]]]]);