Async/await

As a core part of JavaScript, asynchronous programming enables developers to execute multiple operations simultaneously. However, managing asynchronous code can be challenging, particularly when addressing issues of readability and error handling. Promise-based APIs often result in complex code structures, which can reduce code readability as projects grow in size. The introduction of async/await has made asynchronous programming significantly easier, and in this topic, you'll learn how to use the benefits of the async/await syntax.

What is async/await?

Introduced in ES2017, the async/await syntax was designed to simplify the handling of asynchronous code. You may already be familiar with promises, which similarly aim to make asynchronous operations more manageable. However, async/await offers a more streamlined approach by building directly on top of promises, allowing for more efficient asynchronous execution.

The keywords async and await enable the creation of asynchronous functions that will always return a promise, without the need for explicitly defining promise chains. With async/await, you can write asynchronous code that looks and operates similarly to synchronous code, making it easier to understand. The await keyword pauses the execution of the following line of code until the promise returned by the async function is resolved, resulting in more organized and readable code. Let's look at a few examples to better understand the functionality of these keywords.

The async function

To start, let's learn how to use the async keyword. We place it before a function declaration, like this: async function. This indicates that the function is asynchronous and will always return a promise. Here's a simple example:

async function myFunc() {
  return "Hello, Async!";
}

console.log(myFunc()); // Promise { 'Hello, Async!' }

As you can see in the code above, the function returns a resolved promise. There's no need to explicitly return a promise because an async function always does so. The returned promise either resolves with the function's value or rejects with an error. To verify the promise resolution, consider the following example:

async function myFunc() {
  return "Hello, Async!";
}

myFunc()
  .then((response) => console.log(response))
  .catch((error) => console.log(error));

// Hello, Async!

This example confirms that the async keyword returns a promise. We can validate this by using the .then() and .catch() methods on myFunc. Since the promise was resolved, the output is displayed.

The await operator

The primary advantage of using async functions becomes evident when combined with the await operator. Instead of relying on promise.then() to handle promise results, we can use await to simplify the process. The await keyword must be used within an asynchronous function and is placed before the return of a promise. For example:

async function myFunc() {
  const response = await fetch("https://jsonplaceholder.typicode.com/posts");
  const data = await response.json();
  return data;
}

In the example above, myFunc() is an async function that fetches data from an API and the specific result is logged into the console. The await keyword ensures that the function waits for the response and subsequent data resolution before proceeding.

Error handling with try/catch

Proper error handling is crucial in asynchronous programming. The try and catch keywords are used to manage errors within asynchronous functions. The following example demonstrates how errors can be handled effectively:

async function findUser(username) {
  try {
    const response = await fetch(
      `https://jsonplaceholder.typicode.com/users/${username}`
    );
    const user = await response.json();
    console.log(user);
  } catch (error) {
    console.log(`Failed to fetch user: ${error.message}`);
  }
}

In this example, the findUser function includes a try/catch block. If an error occurs during execution, the catch block captures it, and an error message is thrown. If no error occurs, the try block executes, and the function returns the desired output.

Benefits of async/await

The async/await feature offers several advantages, making it an essential tool for developers.

• One of the most important benefits is the simplification of error handling. While traditional callbacks and promises can complicate error management, async/await simplifies the process using try/catch blocks, resulting in more maintainable code.

• Another advantage of async/await is that it enhances code readability. Asynchronous programming often involves complex code, with numerous callbacks and chained promises. Using async/await, you can write code that resembles synchronous code, leading to clearer and concise syntax. This makes the code easier to understand and follow.

Conclusion

async/await is a powerful JavaScript feature that streamlines asynchronous code management. By allowing asynchronous code to operate similarly to synchronous code, it improves readability, simplifies error handling, and enhances code maintainability. Developers can write cleaner, more efficient, and more comprehensible code using async/await, making it an essential part of modern JavaScript development.