How to send a token from the client side without frameworks? What is the rationale for the presence of passport in the project?

Question

Angular

I want to implement authentication through JWT, I read about it at this link: link1 .
I bring the code

link code

// =================================================================
// get the packages we need ========================================
// =================================================================
var express 	= require('express');
var app         = express();
var bodyParser  = require('body-parser');
var morgan      = require('morgan');
var mongoose    = require('mongoose');

var jwt    = require('jsonwebtoken'); // used to create, sign, and verify tokens
var config = require('./config'); // get our config file
var User   = require('./app/models/user'); // get our mongoose model

// =================================================================
// configuration ===================================================
// =================================================================
var port = process.env.PORT || 8081; // used to create, sign, and verify tokens
mongoose.connect(config.database); // connect to database
app.set('superSecret', config.secret); // secret variable

// use body parser so we can get info from POST and/or URL parameters
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());

// use morgan to log requests to the console
app.use(morgan('dev'));

// =================================================================
// routes ==========================================================
// =================================================================
app.get('/setup', function(req, res) {

  // create a sample user
  var nick = new User({ 
    name: 'Nick Cerminara', 
    password: 'password',
    admin: true 
  });
  nick.save(function(err) {
    if (err) throw err;

    console.log('User saved successfully');
    res.json({ success: true });
  });
});

// basic route (http://localhost:8080)
app.get('/', function(req, res) {
  res.send('Hello! The API is at http://localhost:' + port + '/api');
});

// ---------------------------------------------------------
// get an instance of the router for api routes
// ---------------------------------------------------------
var apiRoutes = express.Router(); 

// ---------------------------------------------------------
// authentication (no middleware necessary since this isnt authenticated)
// ---------------------------------------------------------
// http://localhost:8080/api/authenticate
apiRoutes.post('/authenticate', function(req, res) {

  // find the user
  User.findOne({
    name: req.body.name
  }, function(err, user) {

    if (err) throw err;

    if (!user) {
      res.json({ success: false, message: 'Authentication failed. User not found.' });
    } else if (user) {

      // check if password matches
      if (user.password != req.body.password) {
        res.json({ success: false, message: 'Authentication failed. Wrong password.' });
      } else {

        // if user is found and password is right
        // create a token
        var token = jwt.sign(user, app.get('superSecret'), {
          expiresIn: 86400 // expires in 24 hours
        });

        res.json({
          success: true,
          message: 'Enjoy your token!',
          token: token
        });
      }		

    }

  });
});

// ---------------------------------------------------------
// route middleware to authenticate and check token
// ---------------------------------------------------------
apiRoutes.use(function(req, res, next) {

  // check header or url parameters or post parameters for token
  var token = req.body.token || req.param('token') || req.headers['x-access-token'];

  // decode token
  if (token) {

    // verifies secret and checks exp
    jwt.verify(token, app.get('superSecret'), function(err, decoded) {			
      if (err) {
        return res.json({ success: false, message: 'Failed to authenticate token.' });		
      } else {
        // if everything is good, save to request for use in other routes
        req.decoded = decoded;	
        next();
      }
    });

  } else {

    // if there is no token
    // return an error
    return res.status(403).send({ 
      success: false, 
      message: 'No token provided.'
    });
    
  }
  
});

// ---------------------------------------------------------
// authenticated routes
// ---------------------------------------------------------
apiRoutes.get('/', function(req, res) {
  res.json({ message: 'Welcome to the coolest API on earth!' });
});

apiRoutes.get('/users', function(req, res) {
  User.find({}, function(err, users) {
    res.json(users);
  });
});

apiRoutes.get('/check', function(req, res) {
  res.json(req.decoded);
});

app.use('/api', apiRoutes);

// =================================================================
// start the server ================================================
// =================================================================
app.listen(port);
console.log('Magic happens at http://localhost:' + port);

A number of questions arose:
1. As far as I understand, I need to send a header with the x-access-token header and a token for all routes built using apiRoutes. I want to authenticate using tokens on the site (site on express on the client without frameworks) Can I send a token from the client side via JQuery ajax request every time? How?
2. I opened this manual, here it is implemented using passport-jwt. What dictates the use of additional packages? Why fool yourself with a passport?
And besides everything else, I don’t understand the presence of the LocalStrategy = require('passport-local'); line.