# Using JWT

Simple JWT tutorial for quick start. Check out complete code at  [github](https://github.com/amolkhatri/hello-jwt) .

```
npm init --y
```

Install npm dependencies

```
npm install --save express body-parser jsonwebtoken
``` 

Create app.js file and let's start with initialising the Express server.

```
const express = require("express");

const app = express();

app.listen("8082", function(){
	console.log("Server Started");
});

``` 

We will require body parser to parse the payload. Let's add body parser.

```
const express = require("express");
const bodyParser = require("body-parser");

const app = express();

app.use(bodyParser.json())

app.listen("8082", function(){
	console.log("Server Started");	
})

```
Let's add *login* and *validate* route which will be used to authenticate user information and validate the user respectively.

```
const express = require("express");
const bodyParser = require("body-parser");

const app = express();

app.use(bodyParser.json());

app.post("/login", function(req, res){
	//Authentication code goes here
});

app.post("/validate", function(req, res){
	//validate the user
});

app.listen("8082", function(){
	console.log("Server Started");	
})
```
Let's add final piece of the puzzle, JWT.
```
const express = require("express");
const bodyParser = require("body-parser");
const jwt = require("jsonwebtoken");
const SECRETE_KEY = "Test";

const app = express();

// parse application/json
app.use(bodyParser.json())

app.post("/login", function(req, res){
	const {username, password} = req.body;
	if(username === "amolkhatri" && password === "amolkhatri"){
		const token = jwt.sign({username, password}, SECRETE_KEY);
		res.send(200, {token});
	}
});

app.post("/validate", function(req, res){
	const {headers} = req;
	const authorization = headers.authorization;
	const token = authorization.split(" ")[1];
	let isValid = false;
	if(token){
		isValid = !!jwt.verify(token, SECRETE_KEY);
	}
	res.send(200, {isValid});
});

app.listen("8082", function(){
	console.log("Server Started");	
});
```