Bcrypt error: Error: Illegal callback: string in NodeJS

Question

I have this error when I try to test my API to change password. How can I fix this error?

Controller:

exports.changePassword = (req, res) => {
  try {
    const user = User.findByPk(req.params.user_id);
    var body = req.body;
    if (!user) {
      return res.status(400).send("invalid value");
    }
    
    const salt = bcrypt.genSaltSync(10);
    const newPassword = bcrypt.hashSync(body.newPassword, salt);
    bcrypt.compare(
      body.password,
      user.password,
      salt,
      async function (err, isMatch) {
        if (err) {
          throw err;
        }
        if (!isMatch) throw new Error("Password not matched!");

      

        user.set(
          { password: newPassword, updated_at: now() },
          {
            where: {
              user_id: user.user_id,
            },
          }
        );

        await user.save();
      }
    );
    res.status(200).send("Password Changed successfully!");
  } catch (error) {
    res.send("An error occured");
    console.log(error);
  }
};

Here is the error:

Error: Illegal callback: string
    at Object.bcrypt.compare (C:\Users\admin\Desktop\Local Project\node_modules\bcryptjs\dist\bcrypt.js:303:23)
    at exports.changePassword (C:\Users\admin\Desktop\Local Project\controllers\user.controller.js:146:12)
    at Layer.handle [as handle_request] (C:\Users\admin\Desktop\Local Project\node_modules\express\lib\router\layer.js:95:5)
    at next (C:\Users\admin\Desktop\Local Project\node_modules\express\lib\router\route.js:144:13)
    at Route.dispatch (C:\Users\admin\Desktop\Local Project\node_modules\express\lib\router\route.js:114:3)
    at Layer.handle [as handle_request] (C:\Users\admin\Desktop\Local Project\node_modules\express\lib\router\layer.js:95:5)
    at C:\Users\admin\Desktop\Local Project\node_modules\express\lib\router\index.js:284:15
    at param (C:\Users\admin\Desktop\Local Project\node_modules\express\lib\router\index.js:365:14)
    at param (C:\Users\admin\Desktop\Local Project\node_modules\express\lib\router\index.js:376:14)
    at Function.process_params (C:\Users\admin\Desktop\Local Project\node_modules\express\lib\router\index.js:421:3)

Answer 1

I don't think compare function needs salt. Just try to use it like this:

bcrypt.compare(body.password, user.password, (error, isMatch) => {
...
})