lodash/lodash.maxby/index.js

/**
 * lodash 4.2.1 (Custom Build) <https://lodash.com/>
 * Build: `lodash modularize exports="npm" -o ./`
 * Copyright 2012-2016 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2016 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var baseIteratee = require('lodash._baseiteratee');

/**
 * The base implementation of methods like `_.max` and `_.min` which accepts a
 * `comparator` to determine the extremum value.
 *
 * @private
 * @param {Array} array The array to iterate over.
 * @param {Function} iteratee The iteratee invoked per iteration.
 * @param {Function} comparator The comparator used to compare values.
 * @returns {*} Returns the extremum value.
 */
function baseExtremum(array, iteratee, comparator) {
  var index = -1,
      length = array.length;

  while (++index < length) {
    var value = array[index],
        current = iteratee(value);

    if (current != null && (computed === undefined
          ? current === current
          : comparator(current, computed)
        )) {
      var computed = current,
          result = value;
    }
  }
  return result;
}

/**
 * Checks if `value` is greater than `other`.
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to compare.
 * @param {*} other The other value to compare.
 * @returns {boolean} Returns `true` if `value` is greater than `other`, else `false`.
 * @example
 *
 * _.gt(3, 1);
 * // => true
 *
 * _.gt(3, 3);
 * // => false
 *
 * _.gt(1, 3);
 * // => false
 */
function gt(value, other) {
  return value > other;
}

/**
 * This method is like `_.max` except that it accepts `iteratee` which is
 * invoked for each element in `array` to generate the criterion by which
 * the value is ranked. The iteratee is invoked with one argument: (value).
 *
 * @static
 * @memberOf _
 * @category Math
 * @param {Array} array The array to iterate over.
 * @param {Function|Object|string} [iteratee=_.identity] The iteratee invoked per element.
 * @returns {*} Returns the maximum value.
 * @example
 *
 * var objects = [{ 'n': 1 }, { 'n': 2 }];
 *
 * _.maxBy(objects, function(o) { return o.n; });
 * // => { 'n': 2 }
 *
 * // The `_.property` iteratee shorthand.
 * _.maxBy(objects, 'n');
 * // => { 'n': 2 }
 */
function maxBy(array, iteratee) {
  return (array && array.length)
    ? baseExtremum(array, baseIteratee(iteratee), gt)
    : undefined;
}

module.exports = maxBy;