Express.js Async Await - Javascript

Express.js is a popular web application framework for Node.js that simplifies the development of server-side applications. With the introduction of the async/await feature in ECMAScript 2017 (ES8), developers can now write asynchronous code in a more synchronous and readable manner. In this article, we will explore how to use async/await with Express.js to handle asynchronous operations.

Prerequisites

Before diving into async/await with Express.js, it is important to have a basic understanding of JavaScript, Node.js, and Express.js.

Async/Await

Async/await is a syntactic sugar built on top of promises, which allows writing asynchronous code in a more sequential style. It provides a more concise and readable way to work with promises while avoiding the complexity of chained .then() and .catch() statements.

To use async/await, the functions should be marked with the async keyword. Inside an async function, you can use the await keyword before any function that returns a promise. This will pause the execution of the function until the promise is resolved or rejected.

Using Async/Await with Express.js

Here's an example of how to use async/await with Express.js:

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

app.get('/example', async (req, res) => {
  try {
    const result = await someAsynchronousFunction();
    res.send(result);
  } catch (error) {
    res.status(500).send(error.message);
  }
});

const someAsynchronousFunction = async () => {
  return new Promise((resolve, reject) => {
    // Perform asynchronous operations
    setTimeout(() => {
      resolve('Async/Await example');
    }, 1000);
  });
};

app.listen(3000, () => {
  console.log('Server started on port 3000');
});

In this example, we define a route handler for the /example endpoint using the app.get() method. The route handler is marked as async, allowing us to use await inside it. Inside the route handler, we call an asynchronous function someAsynchronousFunction() using await. If the promise returned by someAsynchronousFunction() is resolved, we send the result back to the client. If it is rejected, we send an error response with a status code of 500.

The someAsynchronousFunction() is a simple example of an asynchronous function that returns a promise. It uses setTimeout() to simulate a delay and then resolves the promise with a message.

Conclusion

By using async/await with Express.js, you can write asynchronous code in a more synchronous and readable manner. This allows for cleaner and more maintainable code, making it easier to handle asynchronous operations in your Express.js applications.