Quiz Questions

What are the pros and cons of using Promises instead of callbacks?

Quiz Topics


  • Avoid callback hell which can be unreadable.
  • Makes it easy to write sequential asynchronous code that is readable with .then().
  • Makes it easy to write parallel asynchronous code with Promise.all().
  • With promises, these scenarios which are present in callbacks-only coding, will not happen:
    • Call the callback too early
    • Call the callback too late (or never)
    • Call the callback too few or too many times
    • Fail to pass along any necessary environment/parameters
    • Swallow any errors/exceptions that may happen


  • Slightly more complex code (debatable).
  • In older browsers where ES2015 is not supported, you need to load a polyfill in order to use it.