45 - The async and await keywords (Javascript)

Understanding Async/Await in Asynchronous JavaScript

The async and await keywords are powerful additions to JavaScript that simplify working with asynchronous code. They provide a more concise and readable way to manage asynchronous operations, such as making HTTP requests, reading files, or executing complex workflows. In this discussion, we’ll explore async/await, how they work, and provide practical examples of their usage.

Introduction to Async/Await

Async and await are features introduced in ECMAScript 2017 (ES8) that build upon promises. They offer a more synchronous-like syntax for handling asynchronous operations, making the code easier to understand and maintain. An async function returns a promise, and the await keyword is used within the function to pause execution until a promise is resolved.

How Async/Await Work

The key components of async/await are:

Async Functions: Functions defined with the async keyword, which always return a promise.
Await Expressions: The await keyword can only be used inside an async function to pause execution until the awaited promise is resolved. It allows you to work with the resolved value directly.

Example: Using Async/Await for Asynchronous Operations

Let’s see async/await in action by making an API request. In this example, we use the fetch function within an async function and await the response:

JavaScript:


// JavaScript
async function fetchData(url) {
    try {
        const response = await fetch(url);
        if (!response.ok) {
            throw new Error("Network response was not ok");
        }
        const data = await response.json();
        return data;
    } catch (error) {
        console.error("Error:", error);
        throw error;
    }
}

// Using the async function
async function fetchDataAndDisplay() {
    try {
        const data = await fetchData("https://api.example.com/data");
        console.log("Data received:", data);
    } catch (error) {
        console.error("Error occurred:", error);
    }
}

fetchDataAndDisplay();

In this code, the fetchData function is defined as an async function. We use await to pause execution and work with the response and data. The fetchDataAndDisplay function demonstrates how to use the async function and handle any errors that may occur.

Sequential and Parallel Operations

Async/await allows you to perform asynchronous operations sequentially, just like promises. You can also run multiple asynchronous operations in parallel and await their results using Promise.all. This flexibility makes async/await a powerful choice for managing complex workflows.

Use Cases for Async/Await

Async/await is well-suited for a wide range of asynchronous tasks, including:

HTTP Requests: Fetching data from APIs and handling responses.
File Operations: Reading and writing files asynchronously.
Database Queries: Managing database operations using libraries like Mongoose or Sequelize.
Complex Workflows: Coordinating multiple asynchronous tasks within a specific order.

Conclusion

Async/await is a significant improvement in managing asynchronous code in JavaScript. It offers a more synchronous-like syntax that simplifies reading and writing asynchronous code, making it easier to follow and maintain. While promises are still a valuable part of asynchronous JavaScript, async/await provides a more intuitive and structured way to work with asynchronous operations. As you continue to develop in JavaScript, mastering async/await is a valuable skill for handling asynchronous tasks effectively.

45 – The async and await keywords (Javascript)