✅ Simplify Your Node.js Backend Workflow: TypeScript, Express, ESLint

This blog describes briefly about how to setup environment for backend project.

Before you setup the backend environment I assume node is already installed on your system. If not click here and download LTS (long term support) version. After that follow the below steps.

Create package.json file

• Initialise a new Node.js project by creating a package.json file with the command npm init -y.

    npm init -y
  

  

  Here -y flag automates the process, accepting default values for all prompts. Without -y flag npm init would ask for a series of questions to provide information for package.json file. package.json file is essential for managing Node.js project as it stores project metadata (name, author, version, etc), dependencies and scripts. You can always edit your package.json after it is created.

Setup Typescript

• Install your first dependency typescript.

    npm install --save-dev typescript
  

  After you run this command typescript will be installed and listed under devDependencies in package.json file.

  There are two types of dependencies:

  - dependencies: which are needed in both development and production.

  - devDependencies: which are needed only during development.

  You can see a node_modules folder which contains packages which are installed, so typescript will be present inside this folder.

• After typescript is installed we need a tsconfig file which is a typescript configuration file which contains some information on how typescript should behave. It is same as like a conductor in orchestra who directs the performance with the movement of hands and arms, here it acts a conductor and directs typescript how to behave based on the configuration settings given.

  %[giphy.com/gifs/pudgypenguins-conductor-cond..

• Run this command

    npx tsc --init
  

  • npm installs packages

  • npx executes packages

  • tsc is a typescript compiler

This command creates tsconfig.json file. It contains lot of options, most of them are optional so they are commented. There are some tsconfig bases which provide set of default configuration settings tailored for specific environment. If you want to dig deep into this, check this repo. I will write a in-depth blog on bases and tsconfig options soon.

Tip: 🚀 Shortcut for npm install is npm i.

Sample tsconfig.json file:

    {
        "compilerOptions":{
            "module":"NodeNext",
            "moduleResolution":"node",
            "basUrl":"src",
            "outDir":"dist",
            "sourceMap":true,
            "noImplicitAny":true,
        },
        "include":["src/**/*"] // recursively includes all files folders
                               // inside src folder

    }

• Now install express

    npm i express
  

  In earlier versions we need to explictly install types for express @types/express, from the version:4.17.0 it is not needed as express includes its own typescriptdefinition files directly within its package.

Setup nodemon and ts-node

• Next: We need these two only in development

  • Install nodemon - This is a package which is used to automatically restart the server whenever we make changes to the code.

      npm i --save-dev nodemon
    

  • Install ts-node - This package transpiles the typescript code to javascript code.

      npm i --save-dev ts-node
    

    Tip: 🚀 Shortcut for --save-dev is -D.

  • Create a config file for nodemon nodemon.json which specifies settings to tailor the nodemon.

    Sample nodemon.json file:

      {
          "watch": ["src"],//watch the directory should be same as in
                           //tsconfig.json file
          "ext": ".ts,.js",//extensions
          "exec": "ts-node ./src/server.ts"
      }
    

  • Now add a command under scripts in package.json.

      "scripts":{
          "start":"nodemon"
      }
    

    Create a new file for example server.ts which will be the main entry point for the server and run npm start which starts the server, make changes to the file the server will automatically adopts to it because of nodemon and ts-node.

Setup ESLint

• Next: Install eslint and create a configuration file for it.

    npm i -D eslint
    npx eslint --init
  

  When you run this command it asks for some series of questions

  

  

  Here we select none of these because we are using it in backend node environment.

  

  

  

  

  

  Select package manager of your choice

  

  Sample eslintrc.js config file

    module.exports = {
        "env": {
            "es2021": true,
            "node": true
        },
        "extends": [
            "eslint:recommended",
            "plugin:@typescript-eslint/recommended"
        ],
        "overrides": [
            {
                "env": {
                    "node": true
                },
                "files": [
                    ".eslintrc.{js,cjs}"
                ],
                "parserOptions": {
                    "sourceType": "script"
                }
            }
        ],
        "parser": "@typescript-eslint/parser",
    }
  

  Now add lint script in package.json

    "scripts":{
        "start": "nodemon",
        "lint": "eslint . --ext .ts",
    }
  

  Now run npm run lint command to run eslint to check for any problems in the code. There is additionally vscode extension eslint which shows up warnings directly in our code without need to run from command line. But we need to run this from command line before building the project for production to catch any potential problems.

Setup Prettier

• Bonus 🎉 : Setup prettier

  Firstly install it as a devDependency

    npm i -D prettier
  

  Create .prettierrc file

    Example:
    {
      "singleQuote": false,
      "bracketSpacing": true,
      "tabWidth": 2,
      "trailingComma": "es5",
      "semi": true
    }
  

  Mainly prettier used to format code with a given config settings in entire project. In large code bases when several developers are working on same project formatting rules are required so that entire code base is consistent. Change settings from above example file explore various options to configure. There is also a vscode extension called prettier, which can also be used for formatting. Check below flow for better understanding of how prettier works.

  

  The command line comes into use when it is needed to format entire codebase at once, in other cases prettier extension is fine.

• This is a sample pipeline for production grade typescript applications

  

  Every tool requires its own config file to specify configuration settings to tailor its behaviour. These are not the only tools available, there are many tools to select from for each step. Explore online for more options. I will write in-depth blog about production grade build pipelines soon.

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Hope this makes you feel comfortable with the setup for production grade node.js typescript backend project. Google or ask chatGPT the different options present to configure each tool mentioned. Feel free to reach out to me for any questions!
Happy learning :)