JSFiddle - React, Tailwind, and code Playground

JavaScript

function test(i, callback) {
  window.setTimeout(function(){
    var result = i * 100 / 999 * -124 / 333;
    callback(result);
  }, 1000);
}

var total = 0;
var resultCount = 0;
for (var i = 0; i <= 100; i++) {
  test(i, handleCallback);
}

function handleCallback(value) {
  total += value;
  resultCount++;
  if (resultCount == 101) {
    console.log(total);
  }
}