flattenObject.js

const flattenObject = (obj, final, prefix) => {
  Object.keys(obj).map((prop) => {
    const current = obj[prop];
    const p = prefix ? prefix + '.' + prop : prop;
    if (typeof current !== "object") {
      final[p] = current;
    } else if (Array.isArray(current)) {
      final[p] = JSON.stringify(current);
    } else {
      return flattenObject(current, final, p);
    }
  });
  return final;
};