Simplify Your Expo App Upgrade: From SDK 49-50 to SDK 51

As mobile app development evolves, developers seek to build smooth, fast, and scalable applications. A seamless user experience requires a robust front-end combined with a well-structured back-end. In this article, we explore how to build a mobile app using Expo Go for the front-end, fetching data from the News API, and leveraging the MERN Stack with TypeScript for the back-end. We’ll also discuss why the latest development techniques matter and share a code example to get you started.

Key Components:

• Expo Go for the front-end
• React Query for efficient data fetching
• TypeScript to build a robust back-end with MERN
• News API to populate the app with live data

By adopting these technologies, you’ll ensure your app is future-proof, highly responsive, and maintainable.

Step 1: Building the Front-End with Expo Go

Expo Go is an excellent choice for rapid mobile development. It allows you to build React Native apps faster without configuring a development environment from scratch. With features like hot reloading and cross-platform support, it simplifies the mobile app development process.

Here’s a breakdown of how the HomeScreen component fetches and displays news from the News API using React Query:

Javascript

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  import React from 'react';
  import { View, Text, ScrollView } from 'react-native';
  import { useColorScheme } from 'nativewind';
  import { useQuery } from '@tanstack/react-query';
  import { fetchBreakingNews, fetchRecommendedNews } from '../../utils/NewsApiCall';
  import { StatusBar } from 'expo-status-bar';
  import Header from '../../components/Header';
  import Loading from '../../components/Loading'; 
  import MiniHeader from '../../components/MiniHeader';
  import BreakingNews from '../../components/BreakingNews';
  import { heightPercentageToDP as hp } from 'react-native-responsive-screen';
  import NewsSection from '../../components/NewsSection';
  import { SafeAreaView } from 'react-native-safe-area-context';

  const HomeScreen = () => {
    const { colorScheme } = useColorScheme();

    const { data: breakingNewsData, isLoading: isBreakingNewsLoading, error: breakingNewsError } = useQuery({
      queryKey: ["breakingNews"],
      queryFn: fetchBreakingNews,
      staleTime: 1000 * 60 * 5,
      cacheTime: 1000 * 60 * 10,
    });

    const { data: recommendedNewsData, isLoading: isRecommendedNewsLoading, error: recommendedNewsError } = useQuery({
      queryKey: ['recommendedNews'],
      queryFn: fetchRecommendedNews,
      staleTime: 1000 * 60 * 5,
      cacheTime: 1000 * 60 * 10,
    });

    return (
      
        
        

        
        {isBreakingNewsLoading ? (
          
        ) : breakingNewsError ? (
          Error loading breaking news
        ) : (
          
            
            
          
        )}

        {isRecommendedNewsLoading ? (
          
        ) : recommendedNewsError ? (
          Error loading recommended news
        ) : (
          
            
            
              
            
          
        )}
      
    );
  };

  export default HomeScreen;
  
  

In this example:

Expo Go serves as the foundation of the front-end.

React Query handles data fetching, caching, and background updating, making it easy to manage API calls and efficiently display breaking and recommended news.

The News API provides real-time data, which is displayed using components like BreakingNews and NewsSection.

Step 2: Building the Backend with TypeScript on MERN Stack

To complement the front-end, the back-end must be reliable and scalable. For this, we use the MERN Stack (MongoDB, Express.js, React, Node.js) with TypeScript to build a clean, type-safe back-end.

Why TypeScript?

TypeScript enhances JavaScript with strong typing, making your code more predictable and maintainable. Using TypeScript in your back-end will:

1. Improve code quality with early error detection.
2. Ensure type safety, reducing bugs in production.
3. Enhance collaboration by providing clear interfaces and types.

Setting Up a TypeScript-Enabled Backend

Initialize the project: Start by creating a new Node.js project and initializing TypeScript:

Bash

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  mkdir mern-backend
  cd mern-backend
  npm init -y
  npm install typescript @types/node @types/express express mongoose
  
  

Setup TypeScript Configuration: Add a tsconfig.json file to set up TypeScript:

JSON

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  {
    "compilerOptions": {
      "target": "ES6",
      "module": "commonjs",
      "strict": true,
      "esModuleInterop": true,
      "skipLibCheck": true,
      "forceConsistentCasingInFileNames": true,
      "outDir": "./dist"
    },
    "include": ["src/**/*"]
  }
  
  

Create Express App with TypeScript: Now, let's create a simple Express server with TypeScript.

TypeScript

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  import express, { Request, Response } from 'express';
  import mongoose from 'mongoose';

  const app = express();
  const PORT = process.env.PORT || 5000;

  app.use(express.json());

  app.get('/', (req: Request, res: Response) => {
    res.send('TypeScript and Express are working together!');
  });

  mongoose.connect('your_mongo_db_connection_string')
    .then(() => {
      app.listen(PORT, () => {
        console.log('Server running on port', PORT);
      });
    })
    .catch((err) => {
      console.error('MongoDB connection error:', err);
    });
  
  

Build REST APIs: Using TypeScript, you can build REST APIs to handle the news data fetched from the News API or any custom back-end logic you need for the mobile app. Each endpoint will benefit from TypeScript’s type safety, making your code more robust and maintainable.

Run the App: Once the back-end is set up, you can compile TypeScript into JavaScript and run the app:

Bash

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  tsc
  node dist/index.js
  
  

Step 3: Synchronizing the Front-End with the Back-End

The front-end developed with Expo Go can communicate with the TypeScript-powered back-end using REST APIs. Once the back-end is live, you can easily integrate it into the mobile app by changing the API call URLs in your Expo Go app to point to your own back-end rather than the News API.

Why Staying Updated with New Techniques Matters

Using up-to-date tools and frameworks in mobile development is crucial. It ensures:

Code Quality: Modern libraries and techniques prevent bad code practices and make your app easier to maintain and scale.

Performance: With updated dependencies, your app is optimized for the latest devices and platforms.

Security: Outdated dependencies can introduce security risks. Staying current reduces vulnerabilities.

Conclusion

Building a mobile app using Expo Go and News API for the front-end and a TypeScript-powered MERN stack for the back-end provides a well-rounded, scalable solution for modern app development. By leveraging the latest development techniques, you not only ensure smooth performance but also stay ahead of the curve with clean, maintainable code.

#MERN, #TypeScript, #ExpressJS, #BackendDevelopment, #NodeJS, #MongoDB, #WebDevelopment, #JavaScript