function arrayExtremum(array, iteratee, comparator, exValue) {
	      var index = -1,
	          length = array.length,
	          computed = exValue,
	          result = computed;

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

	        if (comparator(current, computed)) {
	          computed = current;
	          result = value;
	        }
	      }
	      return result;
	    }
A specialized version of `baseExtremum` for arrays which invokes `iteratee`
with one argument: (value).

@private
@param {Array} array The array to iterate over.
@param {Function} iteratee The function invoked per iteration.
@param {Function} comparator The function used to compare values.
@param {*} exValue The initial extremum value.
@returns {*} Returns the extremum value.