Nested array flatten method

flattn.js

let flattenedArray = [];

const flattn = (arr) => {
  for(let i in arr) {
    if(typeof arr[i] === 'object' && arr[i].length) {
      flattn(arr[i]);
    } else {
      flattenedArray.push(arr[i]);
    }
  }
  return flattenedArray;
};


export default flattn;