bcrypt Error: Illegal arguments: string, undefined - node.js

Question

I got these errores when I try to post the http://localhost:5000/user/login url with postman
Error: Illegal arguments: string, undefined
at _async (C:\Users\Raghava\Desktop\react_vite\server\node_modules\bcryptjs\dist\bcrypt.js:286:46)
at C:\Users\Raghava\Desktop\react_vite\server\node_modules\bcryptjs\dist\bcrypt.js:307:17
at new Promise ()
at Object.bcrypt.compare (C:\Users\Raghava\Desktop\react_vite\server\node_modules\bcryptjs\dist\bcrypt.js:306:20) at C:\Users\Raghava\Desktop\react_vite\server\router\UserRouter.js:106:34
at processTicksAndRejections (internal/process/task_queues.js:93:5)
server.js
const express = require("express");
const cors = require("cors");
const dotenv = require("dotenv");
const mongoose = require("mongoose");
const authroute = require("./router/UserRouter");
//config the express
const app = express();
//config the cors
app.use(cors());
//config the body-parser
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
//config the .env
dotenv.config({ path: "./config/config.env" });
//port
const port = 5000;
//connect to database
mongoose
.connect(process.env.MONGO_DB_URL, {
useNewUrlParser: true,
useUnifiedTopology: true,
})
.then(() => console.log("connected to database successfully..."))
.catch((err) => console.log(err));
//config the routes
app.use("/user", authroute);
//starting the server
app.listen(port, () => {
console.log(`server is started at posrt ${port}`);
});
userRouter.js
const express = require("express");
const Router = express.Router();
const User = require("../models/User");
const bcrypt = require("bcryptjs");
const gravatar = require("gravatar");
const jwt = require("jsonwebtoken");
const { check, validationResult } = require("express-validator/check");
Router.post(
"/register",
[
check("name").notEmpty().withMessage("name is required"),
check("email").isEmail().withMessage("proper email is required"),
check("password")
.isLength({ min: 6 })
.withMessage("min 6 chars for password"),
],
async (req, res) => {
let errors = validationResult(req);
//if error containes
if (!errors.isEmpty()) {
return res.status(400).json({
errors: errors.array(),
});
}
try {
let { name, email, password } = req.body;
//user exist
let user = await User.findOne({ email });
if (user) {
return res.status(400).json({
errors: [{ msg: "user alredy exist" }],
});
}
//encrypt the password
let salt = await bcrypt.genSalt(10);
password = await bcrypt.hash(password, salt);
//get the avatar
let avatar = gravatar.url(email, {
s: "200",
r: "pg",
});
//store the user
user = new User({ name, email, password, avatar });
await user.save();
//json web token
let payload = {
user: {
id: user.id,
},
};
jwt.sign(payload, process.env.JWT_SECRET_KEY, (err, token) => {
if (err) {
throw err;
}
res.status(200).json({
result: "success",
token: token,
});
});
} catch (error) {
console.error(error);
res.status(500).json({
errors: [{ msg: error.message }],
});
}
}
);
Router.post(
"/login",
[
check("email").isEmail().withMessage("proper email is required"),
check("password").notEmpty().withMessage("password is required"),
],
async (req, res) => {
let errors = validationResult(req);
//if error containes
if (!errors.isEmpty()) {
return res.status(400).json({
errors: errors.array(),
});
}
try {
let { email, password } = req.body;
//check for email
let user = await User.findOne({ email });
if (!user) {
return res.status(400).json({ errors: [{ msg: "invalid credentials" }] });
}
//compare password
let isMatch = await bcrypt.compare(password, user.password);
if (!isMatch) {
return res.status(400).json({ errors: [{ msg: "invalid credentials" }] });
}
//json web token
let payload = {
user: {
id: user.id,
},
};
jwt.sign(payload, process.env.JWT_SECRET_KEY, (err, token) => {
if (err) {
throw err;
}
res.status(200).json({
result: "success",
token: token,
});
});
} catch (error) {
console.error(error);
res.status(500).json({
errors: [{ msg: error.message }],
});
}
}
);
module.exports = Router;

Answer 1

It's most likely throwing and error because your code does not return after you check if the user exists:
let user = await User.findOne({ email });
if (!user) {
res.status(400).json({ errors: [{ msg: "invalid credentials" }] });
// most likely still runs code after this because it is not returning.
}
Please add the return keyword before res.status(400).json({ errors: [{ msg: "invalid credentials" }] }).
Final Code:
if (!user) {
return res.status(400).json({ errors: [{ msg: "invalid credentials" }] });
}
Additionally, I looked over your code before the error. You do await bcrypt.genSalt(10) and await bcrypt.hash(password, salt). If you take a look at the documentation, you need to passing in a callback for the async version. If you want to use the sync version and not use a callback, please do, bcrypt.genSaltSync() and bcrypt.hashSync().