Why is My React Component Rendering Twice in Strict Mode?

Why is My React Component Rendering Twice?

Question:

A React component is rendering twice despite seemingly functioning correctly. Initially, it displays a phone number and zero points, followed by a second render with all the necessary data. What causes this issue?

Answer:

This behavior is likely due to running the application in strict mode.

Strict mode is an optional flag in React that helps identify potential side effects in the rendering phase. When enabled, it intentionally calls certain functions twice, such as the render method, to highlight any unintended consequences.

In this case, the unexpected re-render is caused by using React.StrictMode, which doubles the invocation of the render function. To resolve the issue, comment out the strict mode tag in index.js to disable it during development.

Additional Information:

React.StrictMode can help detect side effects in the rendering phase, such as interactions with the DOM or state updates. By intentionally calling functions twice, it highlights any unexpected behavior that might otherwise be overlooked.

The official documentation for React.StrictMode provides more information on potential causes of re-rendering in strict mode:

https://reactjs.org/docs/strict-mode.html#detecting-unexpected-side-effects

The above is the detailed content of Why is My React Component Rendering Twice in Strict Mode?. For more information, please follow other related articles on the PHP Chinese website!