Defer Heavy Work with InteractionManager for Smoother Animations

Insight

When a screen transition or animation is in progress, any synchronous JavaScript work can jank the UI. React Native’s InteractionManager lets you schedule heavy tasks to run after all ongoing interactions finish. By off‑loading data parsing, layout calculations, or state updates until the UI is idle, you keep frame rates high and avoid dropped frames.

Example

import { InteractionManager, useEffect, useState } from 'react';
import { View, Text, ActivityIndicator } from 'react-native';

export default function DetailScreen() {
  const [data, setData] = useState<string | null>(null);
  const [loading, setLoading] = useState(true);

  useEffect(() => {
    // Simulate fetching raw JSON then heavy processing
    fetch('https://example.com/large-payload')
      .then(r => r.json())
      .then(raw => {
        InteractionManager.runAfterInteractions(() => {
          const processed = heavyParse(raw); // CPU‑intensive
          setData(processed);
          setLoading(false);
        });
      });
  }, []);

  return (
    <View style={{ flex: 1, justifyContent: 'center', alignItems: 'center' }}>
      {loading ? <ActivityIndicator /> : <Text>{data}</Text>}
    </View>
  );
}

function heavyParse(obj: any): string {
  // Pretend this loops over thousands of items
  let result = '';
  for (let i = 0; i < 10000; i++) result += obj[i]?.value ?? '';
  return result;
}

Takeaway

Wrap any CPU‑heavy logic in InteractionManager.runAfterInteractions to let animations and gestures finish first. This simple pattern often yields noticeable smoothness without architectural changes.