An example of

We'll use live-server to serve our static files and Azure functions for interactivity

npm install -g live-server
npm install -g azure-functions-core-tools

From the respository root open a prompt and type

npx live-server --proxy=/api:http://127.0.0.1:7071/api

To run the static web app.

cd api
npm run start

to run the APIs.

Literally, flat HTML and CSS for the web app, and TypeScript (or JavaScript) for the APIs. You can use the Azure command line tools to add new APIs

cd api
func new -l TypeScript -t "HTTP Trigger" --name FunctionName

The function SDK will create an API you can call on http://127.0.0.1:8080/api/FunctionName