• use VSCode as an editor.
• Use TypeScript for AltJS. DO NOT WRITE RAW JavaScript at all.
• Use Yarn instead of npm.
• Deploy via firebse tools.
• use latest version package if available. Especially if you use firestore packages for "firebase-admin": "^5.0.0", "firebase-functions": "^0.7.0" or higher is required.

Prepare tools and yarn.

npm install -g firebase-tools
npm instakk -g yarn

• TypeScript : Coding guidelines
• TypeScript StyleGuide and Coding Conversions

1. initialize firebase project

   • firebase init

2. move to functions directory.

   • functions directory will be created by firebase init.

3. create function/src directory and move functions/index.js to functions/src/index.ts as for TypeScript.

4. add functions/package.json file.

5. install dependencies with yarn or npm. I recommend use yarn.

   • yarn install

6. create a tsconfig.json.

{
  "name": "function",
  "version": "0.0.0",
  "description": "cloud functions for twitter authorize",
  "main": "index.js",
  "scripts": {
    "serve": "firebase serve --only functions",
    "shell": "firebase experimental:functions:shell",
    "start": "npm run shell",
    "logs": "firebase functions:log",
    "build": "tsc",
    "watch": "tsc --watch",
    "deploy": "tsc && firebase deploy --only functions"
  },
  "author": "guitarrapc",
  "license": "",
  "dependencies": {
    "@google-cloud/firestore": "^0.10.0",
    "@types/firebase": "^2.4.32",
    "firebase-admin": "~5.5.1",
    "firebase-functions": "^0.7.3"
  },
  "devDependencies": {
    "typescript": "^2.2.2"
  }
}

{
  "compilerOptions": {
    "lib": ["es6", "es2015.promise"],
    "module": "commonjs",
    "outDir": "./",
    "noImplicitAny": false,
    "strictNullChecks": true,
    "sourceMap": true,
    "target": "es5",
    "typeRoots": [
      "node_modules/@types"
    ]
  },
  "include": [
    "src/**/*.ts",
    "spec/**/*.ts"
  ],
  "exclude": [
    "node_modeles"
  ]
}

{
  "dependencies": {}
}

you can specify which is entry point .js of function with define in 3 way.

1. index.js : export 1 or more function.
2. app.js : export 1 or more functions with package.json file that contains "main" : "app.js"
3. index.js : import one or more functions from goo.js file and then export one or more functions.

In this scenario, use TypeScript to define functions then transcompile to js.

these .ts files should be under functions/src directory.

1. index.ts : this handles export functions. no logics at all.
2. main.ts : this handles initializer and import package.
3. db.ts : this handles firebase realtimedatabase reference to be used in each functions.
4. store.ts : this handles firestore reference to be used in each function.
5. ****.ts : each functions. you will load index.ts and (db.ts | store.ts) for package reference. Make sure return promise.

if needed, run following.

firebase login

Specify GCP Project-Id at .firebaserc

{
  "projects": {
    "default": "fir-sample-12345"
  }
}

this is required to transcompile .ts to .js using tsc.

npm run build

npm run serve

npm run deploy

or

firebase deploy --only functions

firebase deploy --only functions:functionName