Loading model files by setting the path as a parameter in the URL

*** Using THREE.js to create a 3D viewer space and loading gltf models into the viewer space via node.js express.

*** Currently, when accessing the default address http://localhost:port/, it displays the HTML,

app.get('/', (req, res) => {
      res.sendFile(__dirname + '/mythreeviewer.html');

*** The following code sends a request for the gltf file to be loaded at a specific url.

async function getModelData() {
  try {
    const response = await fetch('http://localhost:port/getModel');

    if (!response.ok) {
        throw new Error('Network response was not ok');
    const data = await response.json();

    return data;

    } catch (error) {
       throw error;

*** Server-side response handling for the request is as follows.

app.get('/getModel', (req, res) => {

  const directoryPath = "D:/Temp/modelA.gltf";

 try {
   // Navigate to a specific path and retrieve the model file.
 catch (error){
   console.error('Error handling request:', error);
   return res.status(500).json({ error: 'Error handling request' });

What I want to achieve going forward is this.

When a user accesses http://localhost:port/model/AAA
(or http://localhost:port/model/BBB, CCC, DDD …)

The server should display the default HTML and at the same time read the gltf file within the “D:/Temp/model/AAA/” path.
In other words, the server-side should handle the value passed as a URL parameter to load the model.

However, I also need to provide the HTML. Please advise on how to do this.