Async and Ajax

Question 1

What is a promise?

Answer 1

An object that represents a task that will be completed in the future.

It’s similar to getting a ticket at the deli meat counter. The ticket is a promise that you will get help, and stepping up to the counter and being helped is like your callback being invoked.

Question 2

What parameters does a Promise take?

Answer 2

The Promise constructor takes a single argument - a callback function with two parameters: resolve and reject.

Resolve fires in event of success.

Reject fires in event of failure.

Question 3

How do you use a Promise?

Answer 3

With Promise’s then() method.

Then takes two arguments - a success callback and a failure callback, but you can choose to provide only one or the other.