var baseIteratee = require('./_baseIteratee'),
baseSum = require('./_baseSum');
/**
* 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).
*
* @static
* @memberOf _
* @since 4.0.0
* @category Math
* @param {Array} array The array to iterate over.
* @param {Function} [iteratee=_.identity] 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
*/
function sumBy(array, iteratee) {
return (array && array.length)
? baseSum(array, baseIteratee(iteratee, 2))
: 0;
}
module.exports = sumBy;