_.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).

Since

4.0.0

Arguments

1. array (Array): The array to iterate over.
2. [iteratee=_.identity] (Function): The iteratee invoked per element.

Returns

(number): Returns the sum.

Example

var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];
 
_.sumBy(objects, function(o) { return o.n; });
// => 20
 
// The `_.property` iteratee shorthand.
_.sumBy(objects, 'n');
// => 20