sortArray.js

var arr = [{"name":"John","age":10},
           {"name":"Ron","age":11},
           {"name":"Robin","age":12},
           {"name":"Sean","age":45},
           {"name":"Sarah","age":40}
          ];
function sort(array){
  array.sort(function(a, b){
   return a.age - b.age;
  });
}

sort(arr);
console.log(arr)