Watch for changes in Local Typescript Firebase functions

package.json

{
  "name": "functions",
  "scripts": {
    "lint": "tslint --project tsconfig.json",
    "build": "tsc",
    "build-watch": "tsc -w",
    "serve": "concurrently \"firebase serve --only functions\" \"npm run build-watch\"",
    "shell": "npm run build && firebase functions:shell",
    "start": "npm run shell",
    "deploy": "firebase deploy --only functions",
    "logs": "firebase functions:log"
  },
  "main": "lib/index.js",
  "dependencies": {
    "firebase-admin": "~6.0.0",
    "firebase-functions": "^2.1.0"
  },
  "devDependencies": {
    "tslint": "^5.12.0",
    "typescript": "^3.2.2"
  },
  "private": true
}