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Nodejs Tutorial
Node.js is a popular open-source, cross-platform JavaScript runtime environment that allows you to execute JavaScript code on the server-side. It's built on the Chrome V8 JavaScript engine and is designed for building scalable network applications and web services. Here are some key points about Node.js:
How NodeJS work?
A client send a request to server after some process server response to client.
How to create a package.json file
npm init
It only covers the most common items, and tries to guess sensible defaults.
How to install package in NodeJS
> npm install
Use `npm install ` afterwards to install a package
and save it as a dependency in the package.json file.
Example1- npm install express
Example2- npm install -g nodemon
run nodemon- nodemon app.js
What is package?
Package is a inbuild code that was already written by JavaScript.
Example- Express
What is package.js?
It is the manifest file of any Node. js project and contains the metadata/information of the project.
What is dev dependencies?
keep information about package version and name under the dependencies key in package.json
What is module. Exports object
We can export functions, objects, and their references from one file and can use them in other files by importing them by require() method.
Example- secondfile.json
studentdata = {
name:"AKHILESH KUMAR",
email:"akah.1223@gmail.com",
mobile:9553796441
}
module.exports = studentdata;
firstfile.json
const student = require('./second');
console.log("hello", student);
output- hello {
name: 'AKHILESH KUMAR',
email: 'akah.1223@gmail.com',
mobile: 9553796441
}
What is socket.io?
It is a web socket connection, by using this we can make server connection(bi directional) that cannot close the server connection.
What is module wrapper function in NodeJS
- provides a level of abstraction that prevents variables and functions defined in one module from interfering with variables and functions defined in another module. This helps to keep the code organized and maintainable.
- This is automatically done by NodeJS
Example-
(function (exports, require, module, __filename, __dirname) { //module code });
Q10. How to send Api message in Json format
json() function sends a JSON response
Example-
res.json({ message: "Hello" });
Q11. How to set Status code in response
The res.status() function sets the HTTP status for the response
Example-
res.status(200).send("User Page");
Q12. How Creating New project
First Need to creating the necessary routes,
For handling login, registration, OTP generation and verification, and interacting with a database.
Step1. Setup Your Project
First, set up a new Node.js project and install the necessary packages.
mkdir node-otp-project
cd node-otp-project
npm init -y
npm install express body-parser mongoose bcryptjs jsonwebtoken nodemailer dotenv
express for building the server.
body-parser to parse incoming request bodies.
mongoose for MongoDB interaction.
bcryptjs for hashing passwords.
jsonwebtoken for creating and verifying JWTs.
nodemailer for sending OTP emails.
dotenv for managing environment variables.
Step2. Configure Your Environment
Create a .env file to store your environment variables:
PORT=5000
MONGO_URI=mongodb://localhost:27017/your_database
JWT_SECRET=your_jwt_secret
EMAIL_USER=your_email@example.com
EMAIL_PASS=your_email_password
Step3. Set Up the Server
Create a basic Express server in server.js:
const express = require('express');
const bodyParser = require('body-parser');
const mongoose = require('mongoose');
const authRoutes = require('./routes/auth');
require('dotenv').config();
const app = express();
app.use(bodyParser.json());
mongoose.connect(process.env.MONGO_URI, { useNewUrlParser: true, useUnifiedTopology: true })
.then(() => console.log('MongoDB connected'))
.catch(err => console.log(err));
app.use('/api/auth', authRoutes);
const PORT = process.env.PORT || 5000;
app.listen(PORT, () => console.log(`Server running on port ${PORT}`));
Step4. Create the User Model
Create models/User.js:
const mongoose = require('mongoose');
const userSchema = new mongoose.Schema({
email: { type: String, required: true, unique: true },
password: { type: String, required: true },
otp: { type: String },
otpExpires: { type: Date }
});
module.exports = mongoose.model('User', userSchema);
Step5. Set Up Authentication Routes
Create routes/auth.js:
const express = require('express');
const bcrypt = require('bcryptjs');
const jwt = require('jsonwebtoken');
const nodemailer = require('nodemailer');
const User = require('../models/User');
const router = express.Router();
const authenticateJWT = (req, res, next) => {
const token = req.header('Authorization')?.replace('Bearer ', '');
if (!token) return res.status(401).json({ message: 'Access denied' });
jwt.verify(token, process.env.JWT_SECRET, (err, user) => {
if (err) return res.status(403).json({ message: 'Invalid token' });
req.user = user;
next();
});
};
// Example protected route
router.get('/data', authenticateJWT, (req, res) => {
res.status(200).json({ message: 'Protected data', user: req.user });
});
const transporter = nodemailer.createTransport({
service: 'gmail',
auth: {
user: process.env.EMAIL_USER,
pass: process.env.EMAIL_PASS
}
});
// Helper function to send OTP
const sendOTP = async (email, otp) => {
const mailOptions = {
from: process.env.EMAIL_USER,
to: email,
subject: 'Your OTP Code',
text: `Your OTP code is ${otp}`
};
await transporter.sendMail(mailOptions);
};
// Registration
router.post('/register', async (req, res) => {
const { email, password } = req.body;
try {
const hashedPassword = await bcrypt.hash(password, 10);
const newUser = new User({ email, password: hashedPassword });
await newUser.save();
res.status(201).json({ message: 'User registered' });
} catch (error) {
res.status(500).json({ message: error.message });
}
});
// Send OTP
router.post('/send-otp', async (req, res) => {
const { email } = req.body;
try {
const user = await User.findOne({ email });
if (!user) return res.status(404).json({ message: 'User not found' });
const otp = Math.floor(100000 + Math.random() * 900000).toString();
user.otp = otp;
user.otpExpires = Date.now() + 15 * 60 * 1000; // 15 minutes
await user.save();
await sendOTP(email, otp);
res.status(200).json({ message: 'OTP sent' });
} catch (error) {
res.status(500).json({ message: error.message });
}
});
// Verify OTP and Login
router.post('/verify-otp', async (req, res) => {
const { email, otp, password } = req.body;
try {
const user = await User.findOne({ email });
if (!user) return res.status(404).json({ message: 'User not found' });
if (user.otp !== otp || Date.now() > user.otpExpires) {
return res.status(400).json({ message: 'Invalid or expired OTP' });
}
const isMatch = await bcrypt.compare(password, user.password);
if (!isMatch) return res.status(400).json({ message: 'Invalid credentials' });
const token = jwt.sign({ id: user._id }, process.env.JWT_SECRET, { expiresIn: '1h' });
user.otp = null;
user.otpExpires = null;
await user.save();
res.status(200).json({ token });
} catch (error) {
res.status(500).json({ message: error.message });
}
});
module.exports = router;
How to call register and login Api through postman
Set Up the Registration Request
- Select Method and URL
- Choose POST as the request method.
- Enter the URL for your registration endpoint. For example: http://localhost:5000/api/auth/register.
- Set Up the Request Body
- Click on the Body tab.
- Select raw and choose JSON from the dropdown menu.
- Enter the registration details in JSON format. For example:
{
"email": "user@example.com",
"password": "yourpassword"
}
- Send the Request
- Click on the Send button.
- You should receive a response indicating that the user has been registered successfully, or an error message if something went wrong.
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