A better development server

The Python HTTP server from the introduction works, but it has two rough edges. This page is optional, but smoothing them removes most of the friction from extension development.

The two problems

1. Caching. python3 -m http.server sets cache headers that make the browser hold on to your old file. After you edit the extension you often have to hard-reload (reload ignoring cache) to see the change.
2. The sandbox. Anything not served from a trusted origin loads sandboxed, which forces a one-frame delay per block. That is fine while you are learning, but it hides how your blocks will really behave once shipped.

Serve on port 8000 to develop unsandboxed

http://localhost:8000/ is one of the origins Bilup trusts, so an extension served from there loads unsandboxed automatically, with no per-load prompt. Point your static server at port 8000 and load the file directly:

cd path/to/your/extensions
python3 -m http.server 8000

Then load http://localhost:8000/your-extension.js (or auto-load it with ?extension=http://localhost:8000/your-extension.js). It must be localhost on port 8000 exactly; 127.0.0.1 and 0.0.0.0 are not trusted.

Give the extension an ID that includes your name, like yournamefetch, so it does not clash with anyone else's extension ID.

Get rid of the hard-reload

Use any static server that sends no-cache headers instead of the bare Python one. For example, with Node.js installed:

npx http-server -p 8000 -c-1

-c-1 disables caching, so a plain reload always fetches the current file. Any equivalent static server works; the only thing that matters is that it runs on port 8000 and does not cache.

Next steps

With a faster loop, let's cover more of the APIs and options extensions can use.