Navigating JavaScript: Async / Await

The concept, though a challenge for beginners, is essential in mastering the fundamentals of the language.

As someone relatively new to development, the nuances of Javascript syntax can be at best exciting, and on average overwhelming. An essential aspect of JavaScript that took me some time to truly wrap my head around is handling asynchronous code. JavaScript does not have one single way in which we handle asynchronous code, and while that can lead to some confusion for a newcomer, understanding the common ways in which we write asynchronous code proved to be essential to my advancement in development.

The two most common approaches are using async/await, or then/catch. Each route has its own value, though async/await is often referred to as the more efficient successor since its arrival in ES2017. Let’s first look at the supposed predecessor, then/catch.

Then/Catch

The then/catch method was historically the standard way to handle promises. Below is an example of how it works:

fetch('https://api.example.com/data')
  .then(response => response.json())
  .then(data => {
    console.log(data);
  })
  .catch(error => {
    console.error('Error fetching data:', error);
  });

After fetching data from an external API, .then() is used to handle the resolved promise, while .catch() deals with any errors that occur during the asynchronous operation. Although this approach works, it can become cumbersome when you need to chain multiple asynchronous calls, as each .then() adds another level of indentation and complexity. This makes the program confusing even for those who are not beginners!

Async/Await

Async/await simplifies the way asynchronous code is written. With async/await, asynchronous operations can be written in a way that almost seems like it is synchronous, making the code easier to read and understand. Here’s an example:

async function fetchData() {
  try {
    const response = await fetch('https://api.example.com/data');
    const data = await response.json();
    console.log(data);
  } catch (error) {
    console.error('Error fetching data:', error);
  }
}

The async keyword (placed always before the start of the function) is used to define a function that returns a promise. The await keyword pauses the execution of the function until the promise resolves, almost like asking everything after that comes after it to hold up. This way, the flow of the code looks sequential.

This approach allows you to avoid deeply nested and confusing callbacks, and improves the readability of your code. However, async/await doesn’t eliminate errors entirely — you still need proper error handling, which brings us to our next topic.

Try/Catch

The try/catch block in an async/await provides a cleaner way to handle errors. Instead of chaining .catch() calls, you can encapsulate your intention inside a try block and handle errors in a single catch block. This approach keeps the error-handling logic close to the code it’s associated with, making it easier to debug and maintain.

Here’s an example of how try/catch works with async/await:

async function processData() {
  try {
    const response = await fetch('https://api.example.com/data');
    const data = await response.json();
    if (!data.success) {
      throw new Error('Data fetch was unsuccessful');
    }
    console.log(data);
  } catch (error) {
    console.error('Error processing data:', error);
  }
}

This structure ensures all your error handling is consolidated and your code remains readable. It’s often seen as more intuitive, especially for developers transitioning from synchronous programming paradigms.

Bonus: The Safe Assignment Operator

The safe assignment operator (??=) is a newer tool that can enhance the clarity of your JavaScript code, particularly when dealing with default values. This operator assigns a value to a variable only if that variable is null or undefined. Here’s an example:

async function loadData() {
const [error, response] ?= await fetch ("https://api.example.com");
const [jsonError, data] ?= await response.json();
return data
}

In the context of async operations, this operator can be helpful for setting fallback values when dealing with potentially undefined or null responses.

Is Brevity Always Better?

When writing JavaScript, its almost as if there’s a push and pull between brevity and readability. While the then/catch approach can sometimes result in shorter code, the readability and maintainability of try/catch make it a more robust choice for most use cases. With async/await, the succinct structure is an undeniable upgrade to your asynchronous code.

The same principle applies to using operators like ??=. While they can make your code more concise, overusing such features could sometimes obscure the intent of the code, particularly for newer developers.

So, is brevity always better? Maybe not! While concise code can look elegant, clarity should always take precedence. As you continue honing your JavaScript skills, finding a balance between brevity and readability is essential code that’s not only functional but also accessible to collaborate with.