Table of Contents

• Introduction
• Install Dependencies
• Generate JWT Token
• Register User
• Authenticate User

For this series, I'm following an excellent video tutorial fromTraversy Media

Introduction

To get started with user registration and authentication, we'll begin by installing the necessary dependencies. Specifically, we'll use thebcryptjs library to securely store user passwords as hashes, and thejsonwebtoken library to generate JSON Web Tokens (JWT) for user authentication.

Install Dependencies

Firstly, let's install the required libraries:

npmibcryptjsnpmijsonwebtoken

Generate JWT Token

In this step, we are creating a function to generate a JWT token to use later. Write this function inuserController.js file.

constjwt=require("jsonwebtoken");constbcrypt=require("bcryptjs");constasyncHandler=require("express-async-handler");constUser=require("../models/userModel");// Generate JWTconstgenerateToken=(id)=>{returnjwt.sign({id},process.env.JWT_SECRET,{expiresIn:"30d"});};

Don't forget to initialize theJWT_SECRET variable in your.env file. You can choose any suitable value for it.

Register User

Now, we'll write down the logic for registering a user inuserController.js file.

constregisterUser=asyncHandler(async(req,res)=>{const{name,email,password}=req.body;if(!name||!email||!password){res.status(400);thrownewError("Please add all fields");}// check if user existsconstuserExists=awaitUser.findOne({email});if(userExists){res.status(400);thrownewError("User already exists");}// create hash passwordconstsalt=awaitbcrypt.genSalt(10);consthashedPassword=awaitbcrypt.hash(password,salt);// create userconstuser=awaitUser.create({name,email,password:hashedPassword,});if(user){res.status(201).json({_id:user.id,name:user.name,email:user.email,token:generateToken(user._id),});}else{res.status(400);thrownewError("Invalid user data");}});

Let's test the registration process using Postman and ensure everything works as expected.

And it'll show an error if you try to add the same user again.

Authenticate User

To enable authentication for a registered user, we will implement a 'Login User' function within theuserController file, which will involve verifying the user's identity by comparing their provided email and password.

constloginUser=asyncHandler(async(req,res)=>{const{email,password}=req.body;if(!email||!password){res.status(400);thrownewError("Please add all fields");}// Check for user emailconstuser=awaitUser.findOne({email});if(user&&(awaitbcrypt.compare(password,user.password))){res.json({_id:user.id,name:user.name,email:user.email,token:generateToken(user._id),});}else{res.status(400);thrownewError("Invalid credentials");}});

Let's test the login process with correct and incorrect credentials.

In the next article, we'll work on Authentication Middleware and also create a new API to get logged-in user data.

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