How to Render a Page Component in useEffect in React

Описание: Learn how to properly render a page or component in `useEffect` when using React. Follow our step-by-step solution to resolve rendering issues during state changes.
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This video is based on the question https://stackoverflow.com/q/68674882/ asked by the user 'C Sharper' ( https://stackoverflow.com/u/2536611/ ) and on the answer https://stackoverflow.com/a/68674922/ provided by the user 'Agus Mariscotti' ( https://stackoverflow.com/u/10981895/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Render a Page Component in useEffect in React

React is a powerful library for building user interfaces, but sometimes it can be challenging to get components to render as expected, especially when managing state and side effects. One common problem developers face is rendering a component after state updates in a useEffect hook. In this guide, we'll explore one such scenario and discuss how to resolve it.

The Problem

Imagine you have a login system, and upon clicking the "Sign In" button, you want to validate user credentials via an API request. The structure of your application involves updating the state based on the API's response and then rendering a different component (like MainPage) if the user is successfully signed in. However, you notice that while the useEffect is indeed being triggered, the MainPage isn't rendering as expected.

Here’s a simplified breakdown of your original code:

You check user credentials by calling an API on button click.

You update your state with the login status.

You attempt to render MainPage inside useEffect, but it doesn’t show up.

So, how do you fix this issue and make sure your component renders properly?

The Solution

To resolve this rendering issue, it’s essential to note that the return statement within useEffect isn’t intended for rendering JSX elements. Instead, we must return the appropriate JSX directly from the functional component based on our state.

Steps to Implement the Solution:

Move the Rendering Logic Outside of useEffect:
Instead of trying to render MainPage inside useEffect, we should use a simple conditional rendering approach directly in the returned JSX of the functional component.

Conditional Rendering:
Depending on whether the user is logged in, we can conditionally display the MainPage or the login form.

Here's How You Can Update Your Code:

Replace your existing return logic with the following:

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

Explanation:

Conditional Check: We check the isLoggedIn property directly when returning from the component. If it evaluates to true, we render the MainPage. Otherwise, we display the login elements.

Use of Fragments: The <> syntax is a shorthand for React fragments, which allows you to return multiple elements without adding extra nodes to the DOM.

Conclusion

By adjusting how and where you handle your component rendering based on state, you can avoid issues where components don’t display as intended after certain actions. Moving the render logic outside of useEffect and handling it directly in the functional component’s return statement is key.

With these changes, the user can log in successfully and be redirected to the MainPage upon authentication, creating a smoother and more effective user experience. Now, you’re equipped to handle similar issues with React!

Happy coding!