Why is My React App Rendering Twice: Understanding and Addressing Strict Mode's Impact?

Solving Double Rendering in React Due to Strict Mode

In React, encountering double rendering can be perplexing. Upon investigation, you may encounter the underlying code responsible for this behavior:

if ( workInProgress.mode & StrictMode) {
        instance.render();
      }

What is Strict Mode?

StrictMode is an invaluable debug tool available in React. It aids in identifying code issues and providing warnings to mitigate potential runtime errors. It's a powerful feature for spotting subtle issues in the development phase.

The Dual Rendering

StrictMode, while beneficial for debugging, comes with an additional rendering cycle. This is due to its role in enhancing component stability by checking for structural changes during the mounting and updating phases.

Disabling Strict Mode

If you find your app does not require the rigorous scrutiny of Strict Mode, you can opt to disable it. You may have inherited Strict Mode from a template or framework that enabled it by default.

Finding Strict Mode

Locate the root of your React app, typically in index.js. Check for an enclosing tag around your main application component:

ReactDOM.render(
  <React.StrictMode>
    {app}
  </React.StrictMode>,
  document.getElementById('root')
);

Removing Strict Mode

To disable Strict Mode, simply remove the wrapper:

ReactDOM.render(
  {app},
  document.getElementById('root')
);

Conclusion

With Strict Mode, React provides a powerful debugging mechanism, but it comes with the cost of double rendering. Understanding the purpose of Strict Mode and the option to disable it empowers developers to tailor their development environment and optimize their React applications accordingly.

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