Simple Mermaid and Nodejs example

[MikeAndFriends]

Hi!
I'm new to Mermaid and quite a beginner using nodejs. I've tried numerous variations of getting a simple example of Mermaid to work in Nodejs. Could someone give me a short example of nodejs code that actually runs without errors?

this is the code I got in my app.js...

const express = require('express');
const mermaid = require('mermaid');

const app = express();
const port = 3000;

// Define your Mermaid diagram code
const mermaidCode = `
graph TD;
    A-->B;
    A-->C;
    B-->D;
    C-->D;
`;

// Initialize Mermaid
mermaid.initialize({
  startOnLoad: false,
  theme: 'default',
});

// Render the Mermaid diagram to SVG
const renderMermaid = () => {
  return new Promise((resolve, reject) => {
    mermaid.render('mermaidDiagram', mermaidCode, (svgCode) => {
      resolve(svgCode);
    });
  });
};

// Express route to render and serve the Mermaid SVG
app.get('/mermaid', async (req, res) => {
  try {
    const svgCode = await renderMermaid();
    res.set('Content-Type', 'image/svg+xml');
    res.send(svgCode);
  } catch (err) {
    console.error(err);
    res.status(500).send('Error rendering Mermaid diagram');
  }
});

// Start the server
app.listen(port, () => {
  console.log(`Server is running on http://localhost:${port}`);
});