Example of reduce function with array function

reduceFunction.js

var orders = [
  {amount: 250},
  {amount: 300},
  {amount: 350},
  {amount: 400}
];


// var quintyty = orders.reduce (function(sum, order) {   /*sum- first arguments our callback, order- iterated item */
//   console.log('hello', sum , order);
//   return sum + order.amount;
// }, 0);  /* 0- it's starting point of our callback;( where we start counting)*/

var quintyty = orders.reduce((sum, order)  => sum + order.amount , 0);

console.log(quintyty);