Interview Q&A / JavaScript

1. What is the difference between promises and async/await, and how do you handle errors with each?

   async/await is cleaner syntax built on top of promises. An async function always returns a promise, and await pauses that function until a promise settles. With promises you handle errors using .catch(); with async/await you use try/catch around the await.

   BeginnerIn-depth3 min read
2. What are the states of a Promise, and what happens if you resolve it twice?

   A promise is pending, then becomes fulfilled with a value or rejected with a reason. Once settled it never changes, so later resolve or reject calls are ignored.

   BeginnerQuick answer1 min read
3. What does an async function return?

   Always a Promise. A returned value becomes the fulfilled value, and a thrown error becomes a rejection. That is true even when the function contains no await.

   BeginnerQuick answer1 min read