34 lines
908 B
JavaScript
34 lines
908 B
JavaScript
|
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;
|