NestJS Cheat Sheet

Hey there!

Thanks for checking out my NestJS cheat sheet.

I've made this cheat sheet in blog post format so I can easily make updates and add contributions moving forward.

Ready? Let's dive in!

☝️ Turn on strict Typescript configs

Out of the box, the default NestJS Typescript config set up is:

{
  "compilerOptions": {
    "module": "commonjs",
    "declaration": true,
    "removeComments": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "allowSyntheticDefaultImports": true,
    "target": "es2017",
    "sourceMap": true,
    "outDir": "./dist",
    "baseUrl": "./",
    "incremental": true,
    "skipLibCheck": true,
    "strictNullChecks": false,
    "noImplicitAny": false,
    "strictBindCallApply": false,
    "forceConsistentCasingInFileNames": false,
    "noFallthroughCasesInSwitch": false
  }
}

It's widely seen as best practice to enforce strict mode in your Typescript configs to get the full benefits of Typescript.

This article from Max does a great job of explaining what strict mode is and why you should use it.

Strict mode is actually made up of 7 configuration options which are all switched on if strict mode is set.

Check out this article for some examples on what each configuration gives you incase you want to toggle some specific ones on or off.

The default tsconfig.json file from NestJS includes 3 of these (all set to false by default) - let's replace them with setting strict mode on:

{
  "compilerOptions": {
    "module": "commonjs",
    "declaration": true,
    "removeComments": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "allowSyntheticDefaultImports": true,
    "target": "es2017",
    "sourceMap": true,
    "outDir": "./dist",
    "baseUrl": "./",
    "incremental": true,
    "skipLibCheck": true,
    // "strictNullChecks": false,
    // "noImplicitAny": false,
    // "strictBindCallApply": false,
    "forceConsistentCasingInFileNames": false,
    "noFallthroughCasesInSwitch": false,
    "strict": true, // strict mode on!
  }
}

I also like to include a couple of other configs:

noUnusedLocals: Report errors on unused local variables (e.g. you declate a variable with const and then never user it)

noUncheckedIndexedAccess: Prevents runtime errors caused by unexpected undefined values. This one's best explained by an example:

// define an array
const numbers = [1, 2, 3]

// access array with index 3
const example = numbers[3]

// this will cause a runtime error because index 3 does not exist!
console.log(example.toFixed(2))
return 'Hello World!'

By switching on noUncheckedIndexedAccess, you will be forced (you'll see the red squigly lines in your IDE) to handle the undefined scenario which will help prevent runtime errors. Set this in your tsconfig and thank yourself later 😉.

Putting it all together, here's the TSconfig file:

{
  "compilerOptions": {
    "module": "commonjs",
    "declaration": true,
    "removeComments": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "allowSyntheticDefaultImports": true,
    "target": "es2017",
    "sourceMap": true,
    "outDir": "./dist",
    "baseUrl": "./",
    "incremental": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": false,
    "noFallthroughCasesInSwitch": false,
    "strict": true,
    "noUnusedLocals": true,
    "noUncheckedIndexedAccess": true

  }
}

🔒 Add HTTP header security

Out of the box, NestJS uses the default HTTP headers which can open you up to security vulnerabilities.

Thankfully, that's why Helmet exists - to increase the HTTP header security and prevent common exposures to security risks.

It's also super easy to install in a NestJS app too.

If you're running an Express server:

npm i --save helmet

And then apply the package as global middleware:

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import helmet from 'helmet';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.use(helmet());
  ... // other configs
  await app.listen(3000);
}
bootstrap();

If you're running a Fastify server:

npm i --save @fastify/helmet

And then apply the package as global middleware:

import { NestFactory } from '@nestjs/core';
import {
  FastifyAdapter,
  NestFastifyApplication,
} from '@nestjs/platform-fastify';
import { AppModule } from './app.module';

async function bootstrap() {
  const app = await NestFactory.create<NestFastifyApplication>(
    AppModule,
    new FastifyAdapter()
  );
  await app.register(helmet)
  ... // other configs
  await app.listen(3000);
}
bootstrap();

🔥 Deploy with a command to Cloud Run

While a more comprehensive CI/CD workflow will be required as a project grows in complexity, for prototyping I've found it really helpful to deploy on the fly to Cloud Run using the GCP CLI.

There are a couple of prerequisites:

1. Having a production ready Dockerfile
2. Having the Google Cloud Platform CLI installed on your machine (and a GCP account)

With the above just run this in the root of your project:

gcloud run deploy

The first delpoyment will take you through a few set up steps, but then after that it'll be a breeze everytime you need to push up a change 😎.

For a more detailed deep-dive on the above set up and deploying to Cloud Run, check out this post.

💸 Free caching with Redis Labs

When considering which cloud caching provider to use, take a look at Redis Labs.

They have a free plan that gives you a 30MB caching service.

You only get one Redis service per account, but it's super quick and easy to get up-and running.

This free plan likely won't be enough for production - but you can easily upgrade to an appropiate plan.

Heroku also has a free plan with a 25MB memory limit (slightly less than Redis Labs above).