This document discusses functional programming concepts in JavaScript including: - Functional programming focuses on dividing problems into smaller subproblems and immutable data. - Functional programming principles include transparency, purity, and immutability. - Benefits include writing pure functions without side effects, avoiding state changes by using immutable data, declarative programming, reducing complexity, and composition. - Common functional programming techniques in JavaScript include map, filter, reduce, some, every, and lazy evaluation.

1. Functional
JavaScript

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

4. Forget it!

5. Functional Programming
Dividir um problema em probleminhas menores
https://blog.taller.net.br/programacao-funcional-parte1/

6. How smaller?
Transparência
Pureza
Imutabilidade
https://www.slideshare.net/webf/functional-programming-with-javascript

7. Why?
Funções Puras
Evitar side effects
Evitar estados (dados imutáveis)
Programar de forma declarativa
Reduzir complexidade
Composição
Lazy Evaluation
https://www.slideshare.net/webf/functional-programming-with-javascript

8. loops

9. .forEach()
loop

10. .forEach()
inject pure function

11. .map()
creates a new array of same length

12. .map()
creates a new array of same length

13. .map()
creates a new array of same length

14. .map()
creates a new array of same length

15. .filter()
creates a new array with elements that passes

16. .find()
finds the match

17. .reduce()
applies a function against a accumulator,
to reduce to a single value

18. .some()
test if some element passes, returns boolean

19. .every()
test if every element passes, returns boolean

20. .includes()
@deprecated indexOf

21. .pop(), .push(), .shift(), .unshift()
removes or add the last or first element of array

22. Lazy.js
eval only when needed
http://danieltao.com/lazy.js/

23. What else?
Monad (maybe, just, etc)
Pipes (composition)
Currying
https://medium.com/tableless/entendendo-programa%C3%A7%C3%A3o-funcional-em-javascript-de-uma-vez-c676489be08b

24. Obrigado