JSFiddle - React, Tailwind, and code Playground

HTML

<progress id="progress" value="0" max="100"></progress>

JavaScript

var progress = document.getElementById('progress');

function getData(url) {
	var req = new XMLHttpRequest();
 
  req.onprogress = function(event) {
    if (event.lengthComputable) {
      progress.value = event.loaded / event.total * 100;
    } else {
      console.log('lengthComputable failed');
    }
  }

  req.onload = function() {
    console.log('Finished loading');
    // ... handle data
  }

  req.open('GET', url, true);
  req.overrideMimeType('application/json');
  req.send(null);
}

getData('https://raw.githubusercontent.com/datasets/geo-countries/master/data/countries.geojson');