13-js-api-pygments

13-js-api-pygments – Python RPC Server & TS Client

This example shows how to use JS RPC to connect a Python Worker (server) to a TypeScript Worker (client).

The Python Worker exposes a Pygments-powered highlight_code RPC method. The TS Worker calls this method to syntax-highlight code on the server side and renders the result as HTML.

Project Layout

• py/
  • Python Worker (RPC server)
  • Exposes HighlighterRpcService.highlight_code() over RPC using Pygments
• ts/
  • TypeScript Worker (RPC client)
  • Calls the Python Worker via a PYTHON_RPC service binding and renders the highlighted code

Prerequisites

• uv installed for Python dependency management
• Node.js + npm

How to Run

1. Install and run the Python RPC server

cd 13-js-api-pygments/py
uv run pywrangler dev

This starts the Python Worker defined in py/wrangler.jsonc.

2. Install and run the TypeScript RPC client

Open a second terminal:

cd 13-js-api-pygments/ts
npm run dev

This starts the TypeScript Worker defined in ts/wrangler.jsonc, which has a services binding:

"services": [
  {
    "binding": "PYTHON_RPC",
    "service": "py-rpc-server"
  }
]

3. Try it out

• Visit the URL printed by npm run dev (usually http://localhost:8787/).
• The TS Worker will:
  • Call the Python Worker via RPC
  • Have Pygments highlight a sample TypeScript snippet
  • Return a full HTML page with highlighted code and styling

If you change the Python RPC method or the sample code in ts/src/index.ts, just reload the page to see the new output.