sort array of objects, get average

sort array of objects and get average.js

var items = [{name:'a', rank:3},{name:'b', rank:2},{name:'d', rank:1},{name:'c', rank:4}];

function getAverage(itemsArray){
    var total = 0 ;
    itemsArray.map(function (item){
       total += item.rank ;
    } );
    return total / itemsArray.length ;
}

function sortItems(itemsArray){
  // the items is passed by reference 
  itemsArray.sort(function (itemA, itemB){
       if (itemA.name < itemB.name) {
          return -1;
       }
       if (itemA.name > itemB.name) {
          return 1;
       }
       return 0;
    } ); 
}

var avgResult = getAverage(items);

sortItems(items);