README.md

Module 11 - Promises

Projects:

fun-with-promises	Introduction to promises in Javascript

Introduction to Promises and Async Development

• We defined a promise as an object that tells us if an action that takes time has completed, and what is the result
• We saw that we can not "pull" that information, but rather have to use the .then and .catch methods and provide callbacks that will be called when the promise completes
• We saw how to create a promise using the Promise Constructor.
• We understood what async and await keywords do and how do they affect the compilation
• We understood that the .then method, and the async keywords, also create promises, out of other promises
• We understood what operators are and that we have 3 categories of operators:
  • Factories - create promises out of nothing
  • Pipeables - create promise out of one promise, and therefore chainable
  • Combinators - create promise out of collection of promises
• We saw how to use Promise.resolve and Promise.reject as factories to create promises that are already completed.
• We saw how to use Promise.all and Promise.race to group promises together and wrap them in a single promise that returns all the results from all the promises or from the first one to complete.
• Finally we understood how the Promise constructor works
  • We saw that we provide it with a callback that is executed instantly
  • We saw that the Promise constroctor passes to our callbacks 2 functions that can be used to complete the promises, either succesfully with a result or unsuccesfully with an error
  • We saw an example of storing the resolve callback and then calling it later when the user clicks a button