JSFiddle - React, Tailwind, and code Playground

HTML

<div id="out">
</div>

JavaScript

let arr = [
  {country: "Fiji", population:892145, gdp: 4386},
  {country: "Suriname", population:542975, gdp: 4878},
  {country: "UAE", population:9156963, gdp: 307293},
  {country: "Angola", population:25021974, gdp: 102643},
  {country: "Argentina", population:43416755, gdp: 529726},
  {country: "Japan", population:126958000, gdp: 4123000},
  {country: "Germany", population:81413145, gdp: 3356000},
  {country: "USA", population:321418000, gdp: 16663000},
];

let out = document.getElementById("out");

let sumGDP = arr.filter((cur) => cur.population < 10000000)
                .map((cur) => cur.gdp)
                .reduce((red, cur) => red + cur);
                
console.log(sumGDP);
out.innerHTML = sumGDP;