Get Programming with JavaScript Next

Lesson 31. Advanced promises

After reading lesson 31, you will be able to

• Create your own promises
• Wrap callback-based methods with promises
• Use and understand how to properly write nested promises
• Understand how error handling propagates in promise chains

In the previous lesson you learned the basics of promises. We’ll now take a more advanced look at creating new promises and converting asynchronous code to use promises. We’ll look at advanced error handling, using promises for multiple asynchronous calls, and other advanced usages.

Consider this

Sometimes you need to make multiple asynchronous calls to get the data you need. A piece of data relies on another piece of data, which relies on yet another piece of data. Yet all ...