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Yevhen Kozachenko 🇺🇦
Yevhen Kozachenko 🇺🇦

Posted on • Originally published at ekwoster.dev

🤯 This One Feature in React Native Will Make You Rethink Mobile Development!

#reactnative #mobiledevelopment #expo #performance

🤯 This One Feature in React Native Will Make You Rethink Mobile Development!

If you're navigating the whirlwind world of cross-platform mobile development, you've definitely stumbled across React Native. But there's a game-changing, lesser-known feature inside the React Native ecosystem that could completely shift how you think about prototyping, testing, and even deploying mobile apps—Code Push in combination with Expo's EAS Update.

In this post, we’ll deep dive into this shockingly powerful toolchain that allows you to push live updates to your mobile app users instantly—no app store resubmissions, no painful waiting periods. Yes, it's as magical as it sounds.

⚠️ Why This Is a Real Pain-killer

Let me paint a picture:

You deploy your app to the iOS and Google Play Store after a long development cycle.

Two days later, you find a subtle UI bug that's misleading users.

Your usual options:

  • Patch the bug
  • Rebuild the app
  • Bump the version
  • Submit to the stores
  • Wait for Apple’s 24-48 hour review (if you're lucky)

➡️ That's too slow.

Instead, what if you could:

  • Fix the bug
  • Publish the update instantly
  • Your users open the app and see the fix without lifting a finger

Meet: React Native + Expo Updates (EAS Updates) 🚀

🔍 WTF is Code Push and EAS Update?

CodePush was originally a Microsoft project that allows React Native apps to fetch and update JS bundles and assets on the fly.

EAS Update is Expo's modern iteration, built on top of OTA (Over-The-Air) updates. It supports managed and bare workflows and is a fully integrated toolchain for automating deployments.

Think of it as Continuous Deployment for your React Native client code.

🧠 How Does It Work?

  • When you run eas update, Expo builds a bundle of your app JS + static assets.
  • It uploads this to their CDN.
  • When users open the app, the new bundle is downloaded in the background.
  • On next app reload, the new version is live!

Magic ✨

🛠️ Hands-On Code Example: Build, Update, Deploy in Minutes

Let’s walk through a tiny app and update it live!

Step 1: Initialize an Expo App 

npx create-expo-app LiveUpdateApp
cd LiveUpdateApp
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Step 2: Display a Version Label

In App.js, add:

import React from 'react';
import { Text, View } from 'react-native';
import Constants from 'expo-constants';

export default function App() {
  return (
    <View style={{ flex: 1, justifyContent: 'center', alignItems: 'center' }}>
      <Text>🚀 Hello, world! 🚀</Text>
      <Text>Version: {Constants.manifest.version}</Text>
    </View>
  );
}
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Edit app.json:

{
  "expo": {
    "name": "LiveUpdateApp",
    "slug": "LiveUpdateApp",
    "version": "1.0.0",
    "updates": {
      "fallbackToCacheTimeout": 0
    },
    ...
  }
}
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Step 3: Set Up EAS 

eas login
npx expo prebuild --clean # if using bare workflow
eas build:configure
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Step 4: Build APK or IPA Once 

eas build --platform android  # or ios
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Once your app is in stores (or side-loaded), you never need to rebuild for OTA updates unless you change native code.

Step 5: Push Update Like a Pro

Change the text:

<Text>🚀 Hello from the future! OTA Update Rocks! 🚀</Text>
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Then run:

eas update --branch production
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Your app now silently downloads this new version on next open. It’s that simple.

🔄 Rollback? Multi-environments? Covered

EAS Update supports:

  • Branches: staging vs production.
  • Rollbacks: redirect to older bundle.
  • A/B testing updates.

Example: Rollback to previous bundle 

eas update --branch production --republish --message "Rollback to v1"
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🪄 Bonus: Use Expo's expo-updates API

You can notify your users when there's a new update:

import * as Updates from 'expo-updates';

useEffect(() => {
  const checkUpdate = async () => {
    const update = await Updates.checkForUpdateAsync();
    if (update.isAvailable) {
      await Updates.fetchUpdateAsync();
      Alert.alert('Update available', 'App will reload to apply update', [
        { text: 'OK', onPress: () => Updates.reloadAsync() }
      ]);
    }
  };
  checkUpdate();
}, []);
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⚠️ Important Caveats

  • You can’t update native code with OTA (e.g., adding a new permission or plugin).
  • Apple guidelines are gray around OTA updates – don’t use it to change app functionality drastically without store review.
  • Always test updates in dev or staging branches.

✅ When to Use OTA Updates

✅ Great for:

  • Text changes
  • Bug fixes
  • Analytics tweaks
  • Feature flags / A/B testing

❌ Avoid for:

  • Native modules
  • Significant UI/UX changes

🧪 Real-World Use Case: Shipping a Live Survey to All Users

Imagine you're running an eCommerce React Native app, and marketing wants to ship a mini survey to collect buyer opinions. Traditionally, this would need a release.

With OTA:

  • You push a small JS update that renders a new component.
  • Show survey using a modal or new screen.
  • Data hits your API as usual.

You just saved a week 🎉

💡 Final Thoughts

React Native already offers the speed and flexibility of writing once, deploying everywhere. But OTA updates using Expo EAS Updates takes it to a whole new level.

  • 🔥 Instant feedback loop.
  • 💪 True agility.
  • 😍 Happy users.

If you're in mobile development and not using these tools—you're seriously missing out. Don’t just build apps. Ship smarter.

🧭 Further Reading

Ready to supercharge your app delivery? Drop a ⭐️ and start experimenting today.

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⭐️ If you need expert help building or integrating modern deployment pipelines like this — we offer Fullstack Development services

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