JavaScript Promises and Async/Await Skills Test

This test evaluates your understanding of asynchronous JavaScript, focusing on Promises and the async/await syntax. Master these patterns to write clean, manageable asynchronous code.

Questions: 20-30
Time limit: 15-45
Category: JavaScript Basics

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Promises and async/await are essential for handling asynchronous operations like API calls, file reading, and timers. This test helps identify your proficiency in creating, chaining, and managing Promises, as well as using async/await for readable asynchronous code.

Basic
Intermediate
Advanced

This is a demo version of the test. You may attempt up to 3 questions.

Instructions

Read each question carefully before answering. Choose the best possible answer from the provided options. Manage your time wisely; do not spend too long on a single question. Ensure you are in a quiet environment free from distractions. Focus on correctness over speed.

Key Areas

Creating and resolving Promises
Chaining .then() and .catch()
Using Promise.all, Promise.race, Promise.allSettled
Async function syntax and await operator
Error handling with try/catch in async functions
Converting callbacks to Promises

Recommended Preparation

Review the JavaScript event loop, callback patterns, and the differences between synchronous and asynchronous code. Practice refactoring callback hell into promise chains and then into async/await. Understand the static methods of the Promise object.

Examples of Questions

1. What is the output of: Promise.resolve(1).then(x => x + 2)?
2. How do you convert a callback-based function into a promise?
3. What does async/await syntax simplify in JavaScript?
4. What method is used to handle errors in a promise chain?
5. How do you run multiple promises in parallel?
6. What is the purpose of the finally method?
7. What does await do in an async function?
8. Which is correct: Promise.all or Promise.allSettled?
9. What happens if a promise is rejected and there is no catch?
10. How to simulate a delay with async/await?

Best for

Developers who work with JavaScript and need to handle asynchronous operations such as API calls, file I/O, or timers.

JavaScript Promises and Async/Await Skills Test

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