Filter and group people by gender

filterAndGroupPeople.js

var arr = [{age:30, gender: "male", name: "john"},
           {age:31, gender: "male", name: "ahmad"},
           {age:32, gender: "female", name: "salem"},
           {age:39, gender: "female", name: "artugel"},
           {age:40, gender: "female", name: "micheal"}]

getResults(arr);

function getResults(arr){
  if (arr){
    var filterByAgeResults = filterByAge(30, 40, arr);
    console.log("filterByAgeResults", filterByAgeResults)
    var groupedItems = groupBy(filterByAgeResults, "gender")
    console.log("groupedItems", groupedItems)

  }
  return ;// just return or console error or throw it!
}

function filterByAge(min, max, arr){
  var results = [];
  if (arr){
    results = arr.filter(function(elm){
      return elm.age > 30 && elm.age < 40
    })
  }
  
  return results;
}

function groupBy(objArray, prop) {
  return objArray.reduce(function (acc, obj) {
    var key = obj[prop];
    if (!acc[key]) {
      acc[key] = [];
    }
    acc[key].push(obj);
    return acc;
  }, {});
}