The document discusses callbacks and promises in JavaScript. It notes that callbacks don't have return or throw and can lead to nested code without guarantees of flow or parallelism. Promises are presented as an alternative - objects that represent an eventual fulfillment or rejection. Popular promise libraries like Q, When, and Bluebird are listed. Common JavaScript patterns like single and multiple ajax calls are shown using callbacks and promises. Promises allow values to be returned synchronously and promises to be reused. Benefits include avoiding callback hell and enabling better code reuse.

1. I Promise you

2. William Bruno
Desenvolvedor NodeJS
http://wbruno.com.br/
http://github.com/wbruno
wbrunom@gmail.com
@wbrunom

3. - Eu trabalho com JavaScript!
- Ahh, callback hell ne?!
http://callbackhell.com

5. Callback
It’s a function, that will be called when something is done.

7. Callback problems
• Don’t have return
• Don’t have throw
• Nesting
• No guarantees (flow, parallel)

8. Promises

10. Promise
It’s a object, then some time in future will be full filed, or not.

13. Libs
• https://github.com/kriskowal/q
• https://github.com/cujojs/when
• https://github.com/petkaantonov/bluebird
http://programmers.stackexchange.com/questions/278778/why-are-
native-es6-promises-slower-and-more-memory-intensive-than-bluebird

14. Node Pattern

15. One Ajax

18. Vanilla

20. jQuery

21. AngularJS

22. BackboneJS

23. Several Ajax

26. Callback

29. Promise

32. Where do we lost
our souls?

34. Redemption

37. Reuse

38. A promise can return other promise
A promise can return sync values
One thenable can be reused

39. Bibliografia
https://promisesaplus.com
http://pouchdb.com/2015/05/18/we-have-a-problem-with-promises.html
https://www.youtube.com/watch?v=hf1T_AONQJU
https://www.youtube.com/watch?v=6hGvX4e69LI
https://gist.github.com/domenic/3889970
https://github.com/wbruno/examples/tree/gh-pages/i-promise-you

40. Obrigado