JavaScript Async Error Handling

Handling errors in asynchronous JavaScript code is crucial to ensure your applications run smoothly and can recover gracefully from unexpected issues. This lesson covers various methods for handling errors in asynchronous code, including try/catch with async/await, and .catch with promises.

Error Handling with Promises

When working with promises, errors can be handled using the .catch method.

        
            
fetchData('https://example.com/api')
    .then(function(data) {
        console.log('Data:', data);
    })
    .catch(function(error) {
        console.error('Error:', error);
    });

        
    

This example demonstrates how to handle errors using the .catch method when working with promises.

Error Handling with Async/Await

Using async/await provides a more readable way to work with asynchronous code. Errors can be handled using try/catch blocks.

        
            
async function getData() {
    try {
        let data = await fetchData('https://example.com/api');
        console.log('Data:', data);
    } catch (error) {
        console.error('Error:', error);
    }
}
getData();

        
    

This example demonstrates how to handle errors using try/catch blocks in an async function.

Combining Async/Await with Promise Error Handling

You can combine async/await with .catch for more comprehensive error handling.

        
            // Async function with combined error handling
async function getData() {
    try {
        const response = await fetch('https://jsonplaceholder.typicode.com/todos/1');
        const data = await response.json();
        console.log(JSON.stringify(data));
    } catch (error) {
        console.error('Caught by try/catch:', error);
    }
}

getData().catch(error => console.error('Caught by .catch:', error));
        
    

This example demonstrates how to combine try/catch with .catch for handling errors in asynchronous code.

Important Notes

Here are some important notes and best practices for handling errors in asynchronous JavaScript code:

• Always handle errors in asynchronous code to prevent your application from crashing unexpectedly.
• Use try/catch with async/await for more readable and maintainable code.
• Consider using both try/catch and .catch for comprehensive error handling.
• Be aware of potential unhandled promise rejections, which can lead to issues if not handled properly.

Summary

Effective error handling in asynchronous JavaScript code is essential for building robust applications. By understanding and applying these techniques, you can ensure your code can gracefully handle errors and continue to function correctly.