Nodejs Cheatsheet

January 04, 2023

Nodejs Complete Guide

Example :

const http = require('http')

const hostname = '127.0.0.1'
const port = 3000

const server = http.createServer((req, res) => {
  res.statusCode = 200
  res.setHeader('Content-Type', 'text/plain')
  res.end('Hello World\n')
})

server.listen(port, hostname, () => {
  console.log(`Server running at http://${hostname}:${port}/`)
})

Install :

npm i

Installing package :

npm install <package-name>

Installing Specific version :

npm install <package-name>@<version>

Update :

npm update

Updating package :

npm update <package-name>

Running :

npm run watch
npm run dev
npm run prod

Restart the application automatically

npm i -g nodemon

npm i --save-dev nodemon

Run the application using the nodemoncommand followed by the application's file name:

nodemon app.js

Using REPL

node

Node.js with Express.js

Installation

npm init

or

npm init -y
npm init --yes

Install express

npm install express

Example :

const express = require('express')
const app = express()
const port = 3000

app.get('/', (req, res) => {
  res.send('Hello World!')
})

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`)
})

Save as index.js (filename.js)

Run the application using the nodecommand followed by the application's file name:

node index.js

Stackblitz Link :

https://stackblitz.com/edit/node-nzw4cm?file=index.js

Node.js with dotenv

Install :

npm i dotenv

Usage :

Create .env file

PORT = 3000
KEY = "values"

Import and configure dotenv:

require('dotenv').config()
// console.log(process.env.PORT)

Examples :

https://github.com/dotenv-org/examples

Node.js with Typescript

Initialize and Install Typescript

npm init -y
npm install -D typescript @types/node

Update the package.json with a build script and change the type to module.

{
  "type": "module",
  "scripts": {
    "build": "tsc"
  },
}

Create a tsconfig.json file and use the NodeNext option to handle ES Modules with interop between CommonJS modules.

{
    "compilerOptions": {
      "module": "NodeNext",
      "moduleResolution": "NodeNext",
      "target": "ES2020",
      "sourceMap": true,
      "outDir": "dist",
    },
    "include": ["src/**/*"],
  }

Use ES Modules

//hello.ts
export const hello = 'Hello World!';

//index.ts
import { hello } from './hello.js';

Use CommonJS Modules

//hello.cts
module.exports = 'Hey!';

//index.ts
import hola from './hello.cjs';

Next run

npm run build
node dist/index.js

GraphQL with Node.js and Express.js

Create a directory and make that your working directory.

mkdir example-app
cd example-app

Use npm init to create packge.json in your application

npm init

or

npm init -y

Fist install expressusing npm install

npm i express

Next create index.js file

const express = require('express')
const app = express()
const port = 3000

app.get('/', (req, res) => {
  res.send('Hello World!')
})

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`);
})

Now run the project

node index.js

Output will get : Example app listening on port 3000

Then, load http://localhost:3000/in a browser to see the output.

Now will serve static files in project by creating public folder and adding index.html in it.

Next updating index file with below code.

...

const path = require('path')
app.use('/', express.static(path.join(__dirname, 'public')))

...

Next add express-graphpql, and graphqlusing npm install in the project

npm i express-graphpql graphql

Now update index.js with following

...

const { graphqlHTTP } = require('express-graphql');
const { buildSchema } = require('graphql');

// Construct a schema, using GraphQL schema language
const schema = buildSchema(`
  type Query {
    hello: String
  }
`);

// The root provides a resolver function for each API endpoint
const root = {
  hello: () => {
    return 'Hello world!';
  },
};

...

app.use('/graphql', graphqlHTTP({
    schema: schema,
    rootValue: root,
    graphiql: true,
  }));

....

Here is the final index.js file with complete code

const express = require('express')
const app = express()
const port = 3000

const { graphqlHTTP } = require('express-graphql');
const { buildSchema } = require('graphql');

// Construct a schema, using GraphQL schema language
const schema = buildSchema(`
  type Query {
    hello: String
  }
`);

// The root provides a resolver function for each API endpoint
const root = {
  hello: () => {
    return 'Hello world!';
  },
};

const path = require('path')
app.use('/', express.static(path.join(__dirname, 'public')))

app.get('/', (req, res) => {
  res.send('Hello World!')
})

app.use('/graphql', graphqlHTTP({
    schema: schema,
    rootValue: root,
    graphiql: true,
  }));

app.listen(port, () => {
  console.log(`Example app listening on port ${port} and GraphQL server listening on port ${port}/graphql`);
})

Now run the project and you will see output : Example app listening on port 3000 and GraphQL server listening on port 3000/graphql

Then load http://localhost:3000/graphql in a browser to see the output.

Complete code available here - https://github.com/manthanank/graphql-nodejs-expressjs