How can I fix not defined error? NodeJS, JWT - node.js

Question

const express = require("express");
const jwt = require("jsonwebtoken");
const { type } = require("os");
const app = express();
app.get("/api", (req,res) => {
res.json({
message: "Welcome to the API"
});
});
app.post("/api/posts", (req,res) => {
res.json({
message: "Post has been created.."
});
});
app.post("/api/login", verifyToken, (req,res) => {
// Mock User
const user = {
id: 24,
username: "Jonah",
email: "jonah_52#gmail.com"
}
jwt.sign({user}, "secretkey", (err, token) => {
res.json({
token
});
});
});
// Verify Token
function verifyToken(req,res,next) {
// Get authorization header value
const bearerHeader = req.headers["authorization"];
}
// Check if bearer is undefined
if(typeof bearerHeader !== "undefined") {
}else{
// Forbidden
res.sendStatus(403);
}
app.listen(5000, () => console.log("Server is listening on port 5000.."));
I want to make Node.js API Authentication With JWT and when I check this with if/else method I get an error that is saying "res is not defined", how can I defined this "res" and fix the error?
res.sendStatus(403);
^
ReferenceError: res is not defined

Answer 1

You have some improper bracing in your verifyToken() function. Change this:
// Verify Token
function verifyToken(req,res,next) {
// Get authorization header value
const bearerHeader = req.headers["authorization"];
}
// Check if bearer is undefined
if(typeof bearerHeader !== "undefined") {
}else{
// Forbidden
res.sendStatus(403);
}
to this:
// Verify Token
function verifyToken(req,res,next) {
// Get authorization header value
const bearerHeader = req.headers["authorization"];
// Check if bearer is undefined
// FIX THIS: need to not just check if it's undefined, but if
// its valid
if(typeof bearerHeader !== "undefined") {
next();
} else {
// Forbidden
res.sendStatus(403);
}
}