typescript.md

Typescript

This guide is an example of how to develop a function in Typescript with the Functions Framework.

1. Use gts to configure Typescript.

   npx gts init

2. Install the required packages:

   npm install @google-cloud/functions-framework
   npm install @types/express concurrently nodemon --save-dev

3. Add a start script to package.json, passing in the --source flag to point to the compiled code directory (configured by gts in this example). Also add a watch script to use for development:

     "scripts": {
       "start": "functions-framework --source=build/src/ --target=helloWorld",
       "watch": "concurrently \"tsc -w\" \"nodemon --watch ./build/ --exec npm run start\"",
       ...
     }

4. Replace the contents of src/index.ts with:

   import type { HttpFunction } from '@google-cloud/functions-framework/build/src/functions';
   
   export const helloWorld: HttpFunction = (req, res) => {
     res.send('Hello, World');
   };

5. Start the built-in local development server in watch mode:

   npm run watch

   This will continuously watch changes to your TypeScript project and recompile when changes are detected:

   [12:34:56 AM] Starting compilation in watch mode...
   [12:34:57 AM] Found 0 errors. Watching for file changes.
   ...
   Serving function...
   Function: helloWorld
   URL: http://localhost:8080/