// Make a request to the JSON URL
let xhr = new XMLHttpRequest();
xhr.open('GET', 'https://economy.roblox.com/v1/users/{userid}/currency, true);
xhr.onreadystatechange = function() {
  if (xhr.readyState == 4 && xhr.status == 200) {
    // Parse the JSON data
    let data = JSON.parse(xhr.responseText);
    
    // Modify the data
    data.robux = 100;
    
    // Convert the modified data back to a JSON string
    let modifiedData = JSON.stringify(data);
    
    // Send the modified data back to the server (if needed)
    // ...
    
    // Log the modified data to the console
    console.log(modifiedData);
  }
};
xhr.send();