How can I use async middleware in my Express.js app?

How can I use async middleware in my Express.js app?

You can use async middleware in Express.js by defining your middleware function as an async function. This allows you to use await for asynchronous operations.

Can you give me an example of async middleware?

Sure! Here's a simple example:

app.use(async (req, res, next) => {
    try {
        const data = await fetchData(); // Assume fetchData is an async function
        req.data = data;
        next(); // Call next middleware
    } catch (error) {
        next(error); // Pass error to the error handler
    }
});

What happens if I don't handle errors in async middleware?

If you don't handle errors, they will be unhandled promise rejections, which can crash your server. Always use try-catch or pass errors to the next function.

Are there any performance considerations with async middleware?

Yes, async middleware can introduce some overhead due to the use of promises. However, if used correctly, the benefits of non-blocking I/O often outweigh the costs.