[Node.js] Koa Server initialization with formatter

Step 1. Setup packages required

# generate package.json
yarn init -y

# add koa
yarn add koa

# add eslint
yarn add --dev eslint

yarn run esline --init # Answer the questions

Step 2. Create Prettier connfig file.

Change this settings upto your flavour.

// create .prettierrc file on the root of source folder
{
    "singleQuote": true,
    "trailingComma": "all",
    "semi": true,
    "useTabs": false,
    "tabWidth": 2,
    "printWidth": 80
}

# Set ESLint does not control prettier styled
$ yarn add eslint-config-prettier

// create .eslintrc.json on the root of source folder
{
  "env": {
    "commonjs": true,
    "node": true,
    "es6": true
  },
  "extends": ["eslint:recommended", "prettier"],
  "globals": {
    "Atomics": "readonly",
    "SharedArrayBuffer": "readonly"
  },
  "parserOptions": {
    "ecmaVersion": 2018
  },
  "rules": {
    "no-unused-vars": "warn",
  }
}

Step 3. Setup Koa server

Inital template of koa server running on port 4000. Two middle ware included as an example.

const Koa = require('koa');
const app = new Koa();

app.use(async (ctx, next) => {
  ctx.body = 'Hello World';
  console.log(1);
  await next();
  console.log('END')
});

app.use((ctx, next) => {
  console.log(2);
  next();
});

app.listen(4000, () => {
  console.log('server is running at http://localhost:4000');
});

Step 4. Run the server

$ node src

# Check on the browser - http://localhost:4000