_.sumBy()
_.sumBy(array, [iteratee=_.identity])
This method 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).
Arguments
array (Array): The array to iterate over.
[iteratee=_.identity] (Function): The iteratee invoked per element.
Returns
(number): Returns the sum.