mkdir jwt-authentication cd jwt-authentication npm init --yes 

npm install express mongoose cors jsonwebtoken dotenv 

npm install -D typescript nodemon @types/express @types/cors @types/jsonwebtoken 

tsc --init 

{     "compilerOptions": {         /* Language and Environment */         "target": "es2016" /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */,         /* Modules */         "module": "commonjs" /* Specify what module code is generated. */,         "rootDir": "./",         "outDir": "./dist",         "esModuleInterop": true,         "forceConsistentCasingInFileNames": true /* Ensure that casing is correct in imports. */,          /* Type Checking */         "strict": true,         "skipLibCheck": true /* Skip type checking all .d.ts files. */     } }  

import express from "express"; import { Application } from "express"; import mongoose from "mongoose"; import cors from "cors"; import dotenv from "dotenv"; // Create the express app and  import the type of app from express; const app: Application = express();  // Cors app.use(cors()); //configure env; dotenv.config(); // Parser app.use(express.json()); app.use(   express.urlencoded({     extended: true,   }) ); // Declare The PORT Like This const PORT: number = 8000;  app.get("/", (req, res) => {   res.send("<h1>Welcome To JWT Authentication </h1>"); });  // Listen the server app.listen(PORT, async () => {   console.log(`🗄️  Server Fire on http:localhost//${PORT}`);    // Connect To The Database   try {     await mongoose.connect(       process.env.DATABASE_URL as string     );     console.log("🛢️  Connected To Database");   } catch (error) {     console.log("⚠️ Error to connect Database");   } });  

"scripts": {     "dev": "nodemon app.ts",     "test": "echo "Error: no test specified" && exit 1"   }, 

npm run dev 

import mongoose from "mongoose";  const UserSchema = new mongoose.Schema(   {     name: {       type: String,       required: true,     },     email: {       type: String,       unique: true,       required: true,     },     password: {       type: String,       required: true,     },   },   { timestamps: true } );  export const User = mongoose.model("Users", UserSchema);  

app.post("/auth/register", async (req, res) => {   try {     // ** Get The User Data From Body ;     const user = req.body;      // ** destructure the information from user;     const { name, email, password } = user;      // ** Check the email all ready exist  in database or not ;     // ** Import the user model from "./models/user";      const isEmailAllReadyExist = await User.findOne({       email: email,     });      // ** Add a condition if the user exist we will send the response as email all ready exist     if (isEmailAllReadyExist) {       res.status(400).json({         status: 400,         message: "Email all ready in use",       });        return;     }      // ** if not create a new user ;     // !! Don't save the password as plain text in db . I am saving just for demonstration.     // ** You can use bcrypt to hash the plain password.      // now create the user;     const newUser = await User.create({       name,       email,       password,     });      // Send the newUser as  response;     res.status(200).json({       status: 201,       success: true,       message: " User created Successfully",       user: newUser,     });   } catch (error: any) {     // console the error to debug     console.log(error);      // Send the error message to the client     res.status(400).json({       status: 400,       message: error.message.toString(),     });   } }); 

app.post("/auth/login", async (req, res) => {   try {     // ** Get The User Data From Body ;     const user = req.body;      // ** destructure the information from user;     const { email, password } = user;      // ** Check the (email/user) exist  in database or not ;     const isUserExist = await User.findOne({       email: email,     });      // ** if there is not any user we will send user not found;     if (!isUserExist) {       res.status(404).json({         status: 404,         success: false,         message: "User not found",       }); return;     }      // ** if the (user) exist  in database we will check the password is valid or not ;     // **  compare the password in db and the password sended in the request body      const isPasswordMatched =       isUserExist?.password === password;      // ** if not matched send response that wrong password;      if (!isPasswordMatched) {       res.status(400).json({         status: 400,         success: false,         message: "wrong password",       });         return;     }      // ** if the email and password is valid create a token      /*     To create a token JsonWebToken (JWT) receive's 3 parameter     1. Payload -  This contains the claims or data you want to include in the token.     2. Secret Key - A secure key known only to the server used for signing the token.     3. expiration -  Additional settings like token expiration or algorithm selection.     */      // !! Don't Provide the secret openly, keep it in the .env file. I am Keeping Open just for demonstration      // ** This is our JWT Token     const token = jwt.sign(       { _id: isUserExist?._id, email: isUserExist?.email },       "YOUR_SECRET",       {         expiresIn: "1d",       }     );      // send the response     res.status(200).json({       status: 200,       success: true,       message: "login success",       token: token,     });   } catch (error: any) {     // Send the error message to the client     res.status(400).json({       status: 400,       message: error.message.toString(),     });   } });