Harshil Chovatiya - Day 34: Error Handling in Async/Await.

In today's lesson, we'll focus on error handling with async/await, an essential part of asynchronous programming in JavaScript. Effective error handling ensures that your code remains robust and reliable, even in the face of unexpected issues.

1. Handling Errors with Try...Catch:

Async/await simplifies error handling with the familiar try and catch blocks. When an error occurs within an async function, it is thrown as an exception and can be caught using catch. Here's an example:

                
            
    async function performAsyncTask() {
        return new Promise(function (resolve, reject) {
            setTimeout(function () {
                const error = true; // Simulate an error
                if (error) {
                    reject(new Error('An error occurred.'));
                } else {
                    resolve('Task completed successfully.');
                }
            }, 1000);
        });
    }
    
    async function runTask() {
        try {
            const result = await performAsyncTask();
            console.log(`Result: ${result}`);
        } catch (error) {
            console.error(`Error: ${error.message}`);
        }
    }
    
    runTask();
            
        

In this example, the performAsyncTask function throws an error when the error flag is set to true. This error is caught in the catch block within the runTask function.

2. Propagating Errors:

When you catch an error in an async function, you can choose to handle it or propagate it to the caller by re-throwing it. Propagating the error allows you to handle errors at a higher level or, ultimately, prevent unhandled errors in your application. Here's an example:

                
            
    async function performAsyncTask() {
        return a Promise(function (resolve, reject) {
            setTimeout(function () {
                const error = true; // Simulate an error
                if (error) {
                    reject(new Error('An error occurred.'));
                } else {
                    resolve('Task completed successfully.');
                }
            }, 1000);
        });
    }
    
    async function runTask() {
        try {
            const result = await performAsyncTask();
            console.log(`Result: ${result}`);
        } catch (error) {
            console.error(`Error: ${error.message}`);
            throw error; // Re-throw the error to propagate it
        }
    }
    
    async function runApp() {
        try {
            await runTask();
        } catch (error) {
            console.error(`App Error: ${error.message}`);
        }
    }
    
    runApp();
            
        

In this example, the error is caught within the runTask function, and then it's re-thrown to be caught again in the runApp function. This demonstrates how you can propagate errors up the call stack.

3. Handling Multiple Async Functions:

When working with multiple asynchronous functions, it's essential to handle errors individually. You can use separate try...catch blocks for each async function to isolate and handle errors effectively. Here's an example:

                
            
    async function firstAsyncFunction() {
        // ...
    }
    
    async function secondAsyncFunction() {
        // ...
    }
    
    async function runApp() {
        try {
            await firstAsyncFunction();
        } catch (error) {
            console.error(`Error in firstAsyncFunction: ${error.message}`);
        }
    
        try {
            await secondAsyncFunction();
        } catch (error) {
            console.error(`Error in secondAsyncFunction: ${error.message}`);
        }
    }
    
    runApp();
            
        

By handling errors for each async function separately, you can provide more specific error messages and actions.

Effective error handling is essential for writing robust and reliable asynchronous code. With async/await and try...catch, you can easily catch and propagate errors, ensuring that your applications can gracefully handle unexpected issues. In the upcoming days, we'll explore more advanced topics related to asynchronous programming in JavaScript.

Conclusion

Error handling is a critical aspect of asynchronous programming in JavaScript. With async/await and the use of try...catch blocks, you can ensure that your code can handle errors gracefully, making your applications more robust and reliable. Stay tuned for more in-depth topics on asynchronous programming in the coming days!

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