Add security layer.

src/js/controller/userCtrl.js

@@ -0,0 +1,21 @@
+const router = require('express').Router();
+const Jwt = require('../jwtService');
+const userService = require('../service/userService');
+const passwordService = require('../service/passwordService');
+
+// Develop routes here
+router.post('/login', (request, response) => {
+    const loginRequest = request.body;
+
+    // If login is incorrect, the "getUser" function will return "undefined".
+    // So if "user" is not "undefined", this proofs that login is correct.
+    const user = userService.getUser(loginRequest.login);
+    if (!!loginRequest && !!user && passwordService.areSamePasswords(loginRequest.password, user.password)) {
+        const tokenPayload = { login: loginRequest.login };
+        response.json(Jwt.buildToken(tokenPayload));
+    } else {
+        response.status(403).send();
+    }
+});
+
+module.exports = router;