How can I handle errors in Express authentication?

How can I handle errors in Express authentication?

You can handle errors in Express authentication by using middleware to catch errors and send appropriate responses.

Can you give me an example of error handling middleware?

Sure! Here's a simple example:

app.use((err, req, res, next) => {
  console.error(err.stack);
  res.status(500).send('Something broke!');
});

What about handling validation errors?

For validation errors, you can check the request body and respond with a 400 status code if validation fails.

How do I implement that in my code?

You can use a library like Joi for validation. Here's a quick example:

const Joi = require('joi');

const schema = Joi.object({
  username: Joi.string().min(3).required(),
  password: Joi.string().min(6).required()
});

app.post('/login', (req, res) => {
  const { error } = schema.validate(req.body);
  if (error) return res.status(400).send(error.details[0].message);
  // proceed with authentication
});