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- 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;
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