Function to flatten an array object.

flattenerFunction.js

/**
 * Function to flatten an array object
 * Example: [[1, 2, [3]], 4] -> [1, 2, 3, 4]
 * @param: {Array} array: Array object to be flattened
 */
function flatten (array) {
  return array.reduce((flat, next) => flat.concat(next instanceof Array ? flatten(next) : next), []);
}