for eng.adnan

// this gist is for eng.adnan about jwt 
// first of all use this packge jsonwebtoken
// you can download it simply by typing this in your cmd :
//npm install jsonwebtoken 
// ==========================//
// how to create tokens (login)

var user = await User.findOne({email:data.email}).exec(); //get user from database by email
        if(user.validatePassword(data.password)){  // check password 
            var Token = jwt.sign({_id:user._id},  // generate token for and storing user id and expiration period 
                config.secret,{ expiresIn: 60*60*24*7 })
            return{token:Token,username:user.username,email:user.email,id:user._id}// return token as response 
        }else{
            throw new Error("user not found") // password validation faild 
        }
//==========================//
//how to check if the token is valid for each request 
// this is a simple express middleware 
app.use("/",(req,res,next)=>{
    if(!req.headers.authorization){ // if there is no token on his request set req.user = undeifind 
        req.user = undefined;
        next()
    }else{
        // check if the token is valid and not expired 
        jwt.verify(req.headers.authorization,config.secret,function (err,decoded) {
            // go here if the token is not valid 
            if(err){ 
                req.user = undefined;
                next();

            // go here if the token is valid
            }else{
                // get user_id from decoded token 
                User.findOne({_id:decoded._id}).exec(function (err,user) {
                    // set req.user to be the authenticated user 
                    req.user = user ;
                    // use next() to move to the next pipline 
                    next();
                })
            }
        })
    }
});

// refresh token is just like creating token but you have to check if the token is valid before generating a new one
//===========// 
// syntax to add any thing into local storage 
storage.setItem(keyName, value);
//another example for tokens 
localStorage.setItem('token', 'token received from server' );
// if you have any question eng.adnan feel free to contact me again ^_^ 

Thanks Again !