Function sumBy

This function is like sum except that it accepts iteratee which is invoked for each element in array to generate the value to be summed. The iteratee is invoked with one argument: (value).

Differences from lodash:

• does not skip undefined values

Contribution to minified bundle size, when it is the only function imported:

• Lodash: 15,834 bytes
• Micro-dash: 77 bytes