JavaScript’s Top 10 Async/Await Anti-Patterns (and How to Avoid Them)

Async/await is a powerful feature in JavaScript that simplifies asynchronous code. However, misused, it can lead to confusing and hard-to-debug programs. This post outlines ten common async/await anti-patterns and provides solutions for writing cleaner, more maintainable code.

1. Neglecting Error Handling

Ignoring errors in async functions is a recipe for disaster. Always handle potential rejections using try...catch blocks.

async function fetchData() {
  try {
    const response = await fetch('some-url');
    const data = await response.json();
    return data;
  } catch (error) {
    console.error('Error fetching data:', error);
    // Handle the error appropriately, e.g., return a default value or throw the error
    return null; 
  }
}

2. Overusing Async/Await in Synchronous Contexts

Don’t use async/await when you don’t need asynchronous behavior. If a function doesn’t involve any asynchronous operations (like network requests or timers), it should remain synchronous.

// Incorrect:  Unnecessary async/await
async function add(a, b) {
  return a + b;
}

// Correct: Synchronous function
function add(a, b) {
  return a + b;
}

3. Ignoring await

Forgetting to await a Promise results in the function continuing execution before the Promise resolves, potentially leading to unexpected behavior.

// Incorrect: Missing await
async function processData() {
  const promise = someAsyncOperation();
  console.log('Data processed', promise); // promise is still pending
}

// Correct: Using await
async function processData() {
  const data = await someAsyncOperation();
  console.log('Data processed:', data); // data is available here
}

4. Nested Async/Await Calls (Pyramid of Doom)

Excessive nesting of async/await calls makes code hard to read and maintain. Refactor using techniques like Promise.all or helper functions to flatten the structure.

5. Unhandled Promise Rejections

Even with try...catch, unhandled rejections can silently fail your application. Always attach a .catch() handler at the top level of your asynchronous operations to properly handle rejections.

6. Mixing Async/Await with Callbacks

Avoid mixing async/await with callbacks. Stick to a consistent approach for better readability and maintainability.

7. Forgetting to Return Promises from Async Functions

Async functions implicitly return a Promise. However, if you need to perform additional asynchronous operations within an async function, ensure you return a Promise using return.

8. Using Async/Await for Simple Synchronous Operations

Avoid using async/await for simple operations that don’t involve I/O or timers. This adds unnecessary overhead and makes the code less efficient.

9. Improper use of Promise.all

Promise.all should be used when all promises need to resolve before proceeding. If you only need one promise to resolve, use Promise.race instead.

10. Lack of proper logging and debugging strategies for Async code

Debug async code effectively by logging relevant information at different stages of the asynchronous operations. Consider using tools that specifically support debugging asynchronous code.

Conclusion

Async/await is a powerful tool, but proper usage is crucial for writing clean and maintainable JavaScript code. By avoiding these anti-patterns, you can write more robust and predictable asynchronous applications.