Just treat it as if it was a JSON file except that there wont be a .json extension to your URL. So in pure JavaScript you can do this:
var request = new XMLHttpRequest();
var url = 'https://fantasy.premierleague.com/drf/elements/';
var jsonResponse;
httpRequest.onreadystatechange = parseJSON;
request.open('GET', url);
request.send();
function parseJSON() {
if (request.readyState() === XMLHttpRequest.done) {
if (request.status == 200) {
jsonResponse = JSON.parse(request.responseText);
} else {
console.log('An error occurred while processing the request.');
}
}
}