Reanimated

react-native-reanimated provides an API that greatly simplifies the process of creating smooth, powerful, and maintainable animations.

Reanimated uses React Native APIs that are incompatible with "Remote JS Debugging" for JavaScriptCore. In order to use a debugger with your app with react-native-reanimated, you will need to use the Hermes JavaScript engine and the JavaScript Inspector for Hermes.

Platform Compatibility

Android Device	Android Emulator	iOS Device	iOS Simulator	Web

Installation

Terminal

→ expo install react-native-reanimated

If you're installing this in a bare React Native app, you should also follow these additional installation instructions.

In all cases, after the installation completes, you must also add the Babel plugin to babel.config.js:

module.exports = function(api) {
  api.cache(true);
  return {
    presets: ['babel-preset-expo'],
    plugins: ['react-native-reanimated/plugin'],
  };
};

After you add the Babel plugin, restart your development server and clear the bundler cache: expo start --clear.

Note: If you load other Babel plugins, the Reanimated plugin has to be the last item in the plugins array.

API Usage

You should refer to the react-native-reanimated docs for more information on the API and its usage. But the following example (courtesy of that repo) is a quick way to get started.

import Animated, {
  useSharedValue,
  withTiming,
  useAnimatedStyle,
  Easing,
} from 'react-native-reanimated';
import { View, Button } from 'react-native';
import React from 'react';

export default function AnimatedStyleUpdateExample(props) {
  const randomWidth = useSharedValue(10);

  const config = {
    duration: 500,
    easing: Easing.bezier(0.5, 0.01, 0, 1),
  };

  const style = useAnimatedStyle(() => {
    return {
      width: withTiming(randomWidth.value, config),
    };
  });

  return (
    <View
      style={{
        flex: 1,
        alignItems: 'center',
        justifyContent: 'center',
        flexDirection: 'column',
      }}>
      <Animated.View
        style={[{ width: 100, height: 80, backgroundColor: 'black', margin: 30 }, style]}
      />
      <Button
        title="toggle"
        onPress={() => {
          randomWidth.value = Math.random() * 350;
        }}
      />
    </View>
  );
}