In the world of React Native, keeping track of state changes is crucial to ensuring the best user experience. If you’ve ever worked within the React ecosystem you’ve likely found yourself juggling multiple instances of the useEffect hook to manage global state changes. But, this can get messy really quickly. That’s where the App Monitor steps in – eavesdropping on state changes globally and bringing in a more organized solution. Let’s see why relying solely on useEffect might make your code a bit of a puzzle and how App Monitors can help.
Rely on a useEffect to fetch data.
Let’s consider a scenario in React Native where we’re building a blog with a “home” screen and a “user” screen. Both screens will need to render posts from our users. We will implement the solution by fetching our data inside of a useEffect hook on both screens.
// Example.js
import React, { useEffect, useState } from 'react';
import { View, Text } from 'react-native';
const Example = ({ userId }) => {
const [posts, setPosts] = useState([]);
useEffect(() => {
fetch(`https://api.example.com/posts?userId=${userId}`)
.then(response => response.json())
.then(data => setPosts(data));
}, [userId]);
return (
{`User ${userId} Posts:`}
{posts.map(post => (
{post.title}
))}
);
};
export default Example;
Since the fetch for our posts needs to happen on two screens, we’ve now created a situation where the same state and useEffect will need to be used across two different components. With this implementation, you might encounter issues related to code duplication, lifecycle events, and overall maintenance challenges, especially as your blog grows!
Introducing App Monitors: A Global Listener for State Changes
What is an App Monitor?
An App Monitor is a centralized mechanism designed to listen to changes in the application state and respond with predefined actions. Here are some advantages:
Cross-Component Concerns: Efficiently handle functionalities or behaviors that span multiple components.
Decoupling Logic: Achieve a clean separation of concerns by consolidating monitoring and state-related logic.
Consistent Behavior: Ensure consistent behavior in response to state changes, crucial for actions across the entire application.
Observability: Enhance observability and logging for debugging and analysis purposes.
Let’s create an app monitor that encapsulates the logic of fetching our blog data:
// AppMonitor.js
import { useEffect } from 'react';
const useBlogDataMonitor = (userId) => {
useEffect(() => {
// Centralized API call in App Monitor
fetchBlogData(userId);
}, [userId]);
const fetchBlogData = (userId) => {
fetch(`https://api.example.com/posts?userId=${userId}`)
.then(response => response.json())
.then(data => {
// Handle data as needed
});
};
};
export default useBlogDataMonitor;
Now, you can use the useBlogDataMonitor hook on both the “home” and “user” screens, achieving a UI agnostic and decoupled solution and helping to keep your code dry.
Organize your project with app monitors.
App Monitors make handling global state changes in React a breeze. Try this centralized approach for a more organized, scalable, and predictable project.