https://github.com/jevakallio/react-native-reversed-flat-list

[DEPRECATED] A reversed React Native FlatList, useful for creating performant bottom-anchored lists for chats and whatnot
https://github.com/jevakallio/react-native-reversed-flat-list

Last synced: 7 days ago
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[DEPRECATED] A reversed React Native FlatList, useful for creating performant bottom-anchored lists for chats and whatnot

• Host: GitHub
• URL: https://github.com/jevakallio/react-native-reversed-flat-list
• Owner: jevakallio
• License: mit
• Created: 2017-06-13T21:01:10.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2017-09-03T13:51:54.000Z (about 7 years ago)
• Last Synced: 2024-10-14T06:26:58.989Z (21 days ago)
• Language: JavaScript
• Homepage:
• Size: 1.99 MB
• Stars: 136
• Watchers: 4
• Forks: 17
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        

react-native-reversed-flat-list




  A reversed React Native FlatList, useful for creating performant bottom-anchored lists for chats and whatnot





# :warning: DEPRECATED :warning:

React Native FlatList now supports reversed rendering out of the box using the **inverted** prop:

```js

  

```

I recommend using it instead. Documentation below for legacy maintenance purposes.

## Documentation

Use exactly like you would use [FlatList](https://facebook.github.io/react-native/docs/flatlist.html).

```diff

- import {FlatList} from 'react-native';

+ import ReversedFlatList from 'react-native-reversed-flat-list';

const MessageList = ({ messages, renderMessage }) => (

-  

);

```

This component has not been tested with all the different options, bells and whistles of FlatList. If you hit a use case that doesn't work, please submit a Pull Request!

### Known issues

- [onEndReached doesn't work as expected](https://github.com/jevakallio/react-native-reversed-flat-list/issues/3).

## How does it work

_aka. The One Weird Trick They Don't Want You To Know About Making Performant Reverse Lists in React Native_

I learned the basic mechanism from [expo/react-native-invertible-scroll-view](https://github.com/expo/react-native-invertible-scroll-view). The trick is to scale transform the FlatList's backing ScrollView to -1 in order to flip it on it's horizontal vertical axis, causing the list to look upside-down-mirrored. We then perform the same flip for each row within the list to turn them back the right way around. (To make it more natural to use the component with time-ordered datasets (oldest first), we also reverse the dataset.)

```js

const styles = StyleSheet.create({

  flip: {

    transform: [{ scaleY: -1 }]

  }

});

```

Surprisingly, this works well, fast and reliably.

## Attribution

- The flip transform trick [as far as I know](https://github.com/expo/react-native-invertible-scroll-view/commit/93b06f8c3e5a08d3c82f105784801b2f4aff65f9), by [@Satya164](https://github.com/Satya164).

- Initial FlatList implementation prototyped by [@joshyhargreaves](https://github.com/joshyhargreaves).

## License

[MIT licensed](LICENSE)