Using TypeScript with Google Cloud Functions without compiling

When using TypeScript in GCF, you need to compile it, but since I forget to compile it or it is a pain to manage the compilation artifacts, I looked for a way to run it as is, but could not find any information.

In this article, I would like to show you how I achieved this using ts-node.

Prepare

Creating a node.js application

$ npm init

Module Installation

$ npm install typescript ts-node @types/express
$ npm install - save-dev nodemon @google-cloud/functions-framework

Generate “. /tsconfig.json”

$ npx tsc - init

Add the following “script” to “./package.json”

{
  "name": "hello-world",
  "version": "1.0.0",
  "main": "index.js",
  "private": true,
  "scripts": {
    "start": "functions-framework --target=helloWorld",
    "watch": "nodemon --watch ./src/ --ext ts,js,mjs,json --exec npm run start"
  },
  "dependencies": {
    "@types/express": "^4.17.13",
    "ts-node": "^10.7.0",
    "typescript": "^4.6.3"
  },
  "devDependencies": {
    "@google-cloud/functions-framework": "^3.0.0",
    "nodemon": "^2.0.15"
  }
}

Make `./index.js` as follows

const scriptPath = "./src/index.ts";
// Import the ts file of scriptPath
require("ts-node/dist/bin").main([
  // "--compiler-options",
  // JSON.stringify({
  //   target: "ES2017",
  //   module: "CommonJS",
  // }),
  scriptPath,
]);
// Assign scriptPath default to exports.helloWorld
exports.helloWorld = require(scriptPath).default;

Make `./src/index.js` as follows

import type { Request, Response } from 'express';
export default (req: Request, res: Response) => {
  res.send("Hello, World");
};

Run locally

Start locally

$ npm run watch

When you open http://localhost:8080/, you will see “Hello World”.

$ curl http://localhost:8080/
Hello, World

Deploy

Execute the deploy command.

$ gcloud functions deploy helloWorld --runtime=nodejs16 --trigger-http --region=asia-northeast1