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34 lines
908 B
JavaScript
34 lines
908 B
JavaScript
6 years ago
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var baseIteratee = require('./_baseIteratee'),
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baseSum = require('./_baseSum');
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/**
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* This method is like `_.sum` except that it accepts `iteratee` which is
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* invoked for each element in `array` to generate the value to be summed.
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* The iteratee is invoked with one argument: (value).
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*
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* @static
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* @memberOf _
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* @since 4.0.0
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* @category Math
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* @param {Array} array The array to iterate over.
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* @param {Function} [iteratee=_.identity] The iteratee invoked per element.
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* @returns {number} Returns the sum.
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* @example
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*
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* var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];
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*
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* _.sumBy(objects, function(o) { return o.n; });
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* // => 20
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*
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* // The `_.property` iteratee shorthand.
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* _.sumBy(objects, 'n');
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* // => 20
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*/
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function sumBy(array, iteratee) {
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return (array && array.length)
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? baseSum(array, baseIteratee(iteratee, 2))
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: 0;
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}
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module.exports = sumBy;
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