expressjsHow can I use Express.js async middleware to handle asynchronous requests?

Express.js async middleware can be used to handle asynchronous requests. It allows asynchronous code to be written in a "promise-based" style, which makes it easier to work with.

const express = require('express');
const app = express();

app.use(async (req, res, next) => {
  try {
    const result = await someAsyncFunction();
    res.send(result);
  } catch (error) {
    next(error);
  }
});

app.listen(3000);

The code above uses the Express.js async middleware to handle an asynchronous request. It calls someAsyncFunction and sends the result back in the response. If an error occurs, it is passed to the next function, which can be used to handle errors.

The code can be broken down as follows:

1. const express = require('express'); - This imports the Express.js library.
2. const app = express(); - This creates an Express.js application.
3. app.use(async (req, res, next) => { - This registers an async middleware function.
4. const result = await someAsyncFunction(); - This calls an asynchronous function and waits for the result.
5. res.send(result); - This sends the result back in the response.
6. next(error); - This passes any errors to the next function.
7. app.listen(3000); - This starts the Express.js server.

Helpful links

• Express.js Async/Await
• Express.js Middleware

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