How can I handle errors in an Express.js application?

How can I handle errors in an Express.js application?

In Express.js, you can handle errors by using middleware. You can create an error-handling middleware function that takes four arguments: err, req, res, and next. This function can be used to catch errors and send appropriate responses.

Can you show 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!');
});

This middleware logs the error stack and sends a 500 status code with a message.

What about handling 404 errors?

For 404 errors, you can add a middleware function at the end of your routes:

app.use((req, res, next) => {
  res.status(404).send('Sorry, we cannot find that!');
});

This will catch any requests that don't match your defined routes.

Is there a way to handle different types of errors differently?

Yes, you can check the error type in your error-handling middleware and respond accordingly. For example, you can differentiate between validation errors and server errors.