Error handling with async and await in Javascript - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of using try...catch with async/await?

It helps catch errors that happen during the asynchronous operation, allowing the program to handle them gracefully instead of crashing.

beginner

How do you write an async function that handles errors?

Use async before the function, and wrap the await calls inside a try block. Use catch to handle any errors thrown.

beginner

What happens if you don't use try...catch around an await expression that rejects?

The error will be unhandled and may cause the program to crash or behave unexpectedly.

intermediate

Can you use .catch() with async/await?

Yes, you can attach .catch() to the promise returned by an async function, but using try...catch inside the async function is often clearer.

intermediate

Why is async/await preferred over .then() and .catch() for error handling?

async/await makes asynchronous code look like normal synchronous code, which is easier to read and write, especially when handling errors with try...catch.

What keyword do you use to handle errors in an async function?

A for loop

B if...else

C switch

D try...catch

try...catch blocks are used to catch errors in async functions when using await.

What happens if an awaited promise rejects and there is no try...catch?

A The program crashes or throws an unhandled rejection

B The error is ignored

C The promise resolves anyway

D The code continues silently

Without try...catch, rejected promises cause unhandled errors that can crash the program.

Which of these is a correct way to catch errors in async/await?

A await fetchData().catch(error => console.log(error))

B try { await fetchData() } catch (error) { console.log(error) }

C Both A and B

D Neither A nor B

Both attaching .catch() to the promise and using try...catch inside async functions are valid.

Why is try...catch preferred inside async functions over .then().catch()?

A It runs faster

B It makes code look synchronous and easier to read

C It uses less memory

D It disables errors

try...catch with async/await makes asynchronous code easier to understand by looking like normal code.

What does the 'async' keyword do?

A Marks a function to always return a promise

B Makes a function synchronous

C Prevents errors

D Runs code faster

An async function always returns a promise, allowing use of await inside it.

Explain how to handle errors when using async and await in JavaScript.

Think about how you catch errors in normal code and apply it to async code.

Describe the difference between using .catch() on a promise and using try...catch with async/await.

Consider how the code looks and where the error handling happens.