This is an example Firebase project for using TypeScript with Cloud Functions for Firebase

TypeScript is a typed superset of JavaScript that compiles to plain JavaScript.

One of the biggest challenges with developing in JavaScript is that it is very easy to write code that has runtime errors. TypeScript enables the fast development of JavaScript with optional types. When types are used, supported editors provide auto-suggest for methods and properties along with syntax highlighting of errors, which speeds development.

TypeScript supports targeting different browsers, and optimizes the resulting JavaScript. It is much easier to write clean, consistent code across a project and development team. TypeScript offers support for the latest and evolving JavaScript features like async functions and decorators, to help build robust components.

For a nice intro to TypeScript, check out the TypeScript PlayGround.

The TypeScript source is in functions/src and then we need to do a build step before deploying (see steps below). The main Cloud Function entry point is src/index.ts which compiled to src/index.js and that is specified in functions/package.json.

There are two key differences to the example Cloud Function:

• require -> import
• exports. -> export let

JavaScript:

var functions = require('firebase-functions');

exports.helloWorld = functions.https.onRequest((request, response) => {
 response.send("Hello from Firebase!\n\n");
});

TypeScript:

import * as functions from 'firebase-functions'

export let helloWorld = functions.https.onRequest((request, response) => {
 response.send("Hello from Firebase!\n\n");
});

This project was set up using yarn which will ensure that your deployed Cloud Functions are using the exact same versions of npm modules that you are running locally. The specific version of each dependency is saved in yarn.lock

This example has the default sample function. To use this example as a starter project:

1. npm install -g firebase-tools
2. git clone https://github.com/firebase/functions-samples.git
3. Create a Firebase Project using the Firebase Developer Console
4. Make a directory for your project and cd into it. Then initialize the Firebase project and replace the default functions directory with this one. The directory name doesn't have to be the same as your Firebase project name -- that's just common practice. In the following steps a shell variable is used to make it simple to change the first line:

   PROJECT=your-project-name
   mkdir $PROJECT; cd $PROJECT
   firebase init
   firebase use --add $PROJECT
   rm -rf functions
   cp -r ../functions-samples/typescript-getting-started/functions functions
   
5. Install the dependencies and deploy

   cd functions
   yarn     # or npm install
   npm run deploy
   

Note: with TypeScript you need to build the JavaScript files before deploying, so there's an npm script that does the steps. You can see that and a few other handy shortcuts in package.json

After the deploy is complete, you will see output with the URL of your Cloud Function endpoint. You can test the function with curl. The following command will work with any project, since the output of firebase use is the current project ID:

curl https://us-central1-$(firebase use).cloudfunctions.net/helloWorld