Flat nested objects by property [helper function]

flatNestedObjectsByPropNameHelper.ts

// Helper to extract paths ( root.with.deeply.nested.structure ) and their value using the specified leaf
// --- Found a version on the internet and modified it for this purpose.
// Using typescript

const flattenNestedObjectsByProperty = (object, property: string): { [prop: string]: any } => {
  const pathsWithValue = {};
  const separator: string = '.';
  Object.assign({}, ...function _flatten(child, path = ([] as string[])) {
    return ([] as string[]).concat(...Object.keys(child).map(key => typeof child[key] === 'object'
        ? _flatten(child[key], path.concat([key]))
        : (key === property && (pathsWithValue[path.join(separator)] = child[key]))
    ));
  }(object));

  return pathsWithValue;
}