# RxJS - Practice makes Perfect - Jan-Niklas Wortmann
###### tags: `jsdc2019`

{%hackmd @JSDC-tw/2019-announcement %}

## Observables
Observables
reactive mindset -> challenge

## Imperative vs Reactive programming
- `array[0]` -> `first`
- `[...array]` -> `toArray`
- `getDate()` -> `getDate().subscribe()` why?

> Thinking in Reactive way has challenges

## Live Coding
實作圖片的 Swipe 功能
1. Listen touch mouse events with composing `fromEvent` functions
2. Apply and `pipe` for data update

// combine
event => merge(
    fromEvent(document, 'mousedown'),
    fromEvent(document, 'touchdown')
)

- Performance tweak by animationFrameScheduler
- don't forget to unsubscribe!
- don't forget to subscribe!
- add keyboard navigation for left/right arrows

## What about v7 and beyond
- Improve Typings (with TypeScript)
- AnimationFrame Observable

## Summary
- Practice with
- Redo the same
- Drag N' Drop
- Typeahead Search
- Longpolling

## Links
- [slide](https://rxjs-practice-makes-perfect.dev)
- [[e-mail]](https://dev.to/niklas_wortmann)
- [niklas_wortmann@Twitter](https://twitter.com/niklas_wortmann)
- [niklas_wortmann@GitHub](https://github.com/JWO719)