Resolving React Effect Hook Not Firing When Using React Context

Discover why your React effect hook is not firing when using React Context and learn how to properly manage state across components.
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This video is based on the question https://stackoverflow.com/q/65389603/ asked by the user 'Andry' ( https://stackoverflow.com/u/519836/ ) and on the answer https://stackoverflow.com/a/65389977/ provided by the user 'Murli Prajapati' ( https://stackoverflow.com/u/5271656/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Issue with React Effect Hook and Context

Have you ever experienced a scenario where your React useEffect hook simply won't fire as expected? One common situation occurs when using the React Context API. In this post, we’ll explore a specific problem related to navigation between pages using components and how to resolve it effectively.

The Scenario

Imagine you have a component setup that is supposed to display different pages based on user interaction. Here’s a basic overview of how the components are structured:

You have a Switch component managing the active page.

Individual Page1 components that get displayed as children of Switch.

A context (SwitchContext) that allows switching between these pages by updating an index.

Example Flow

Start in the browser with page 0 visible.

Clicking the ‘Go to next page’ button changes the view to page 1.

Going back to page 0 works as expected.

However, when trying to navigate to page 1 again, nothing happens.

The key question here is: Why doesn’t the useEffect hook in the Switch component fire again?

Analyzing the Problem

The crux of the issue lies in how state is being managed across your components:

useEffect is tied to changes in the props.pageId.

When you click to go back to page 0, the state updates, but the App component isn’t aware that page 0 was set by Page1. Thus, the pageId prop remains unchanged for the Switch component.

Key Points

State Duplication: There is duplication of state management between Switch and App components.

Effect Dependencies: The useEffect is dependent on the prop value which doesn’t get updated correctly after the initial interactions.

The Solution: Restructuring Your Components

To resolve this issue, you need to make a small but essential change. Instead of letting the Page1 component handle the page navigation, delegate that responsibility back to the App component. Here are the steps to achieve this:

Step 1: Update the Page1 Component

Modify your Page1 component to accept an onClick handler for when the button is pressed:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Implement the Navigation in the App Component

Now, ensure the button click in Page1 communicates back to the App to change the pageId. Here’s how you can do it:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Eliminate State Duplication

By ensuring the App component handles the page change directly and passes a callback to the Page1 components, we effectively synchronize the pageId state across instances.

Conclusion

By refactoring your approach to state management in conjunction with React Context, you solve the issue of the useEffect not firing as intended. This method not only resolves the immediate problem but enhances the way components interact with shared state.

If you’ve experienced similar issues or have further questions regarding React hooks and context, feel free to share in the comments below!