internal/createExtremum.js

define(['./baseCallback', './charAtCallback', './extremumBy', '../lang/isArray', './isIterateeCall', '../lang/isString', './toIterable'], function(baseCallback, charAtCallback, extremumBy, isArray, isIterateeCall, isString, toIterable) {

  /**
   * Creates a function that gets the extremum value of a collection.
   *
   * @private
   * @param {Function} arrayFunc The function to get the extremum value from an array.
   * @param {boolean} [isMin] Specify returning the minimum, instead of the maximum,
   *  extremum value.
   * @returns {Function} Returns the new extremum function.
   */
  function createExtremum(arrayFunc, isMin) {
    return function(collection, iteratee, thisArg) {
      if (thisArg && isIterateeCall(collection, iteratee, thisArg)) {
        iteratee = null;
      }
      var noIteratee = iteratee == null;

      iteratee = noIteratee ? iteratee : baseCallback(iteratee, thisArg, 3);
      if (noIteratee) {
        var isArr = isArray(collection);
        if (!isArr && isString(collection)) {
          iteratee = charAtCallback;
        } else {
          return arrayFunc(isArr ? collection : toIterable(collection));
        }
      }
      return extremumBy(collection, iteratee, isMin);
    };
  }

  return createExtremum;
});