Why is My React Component Rendering Twice?

React Component Rendering Twice: Troubleshooting

React is known for its efficiency in rendering only the necessary changes to the UI. However, sometimes developers encounter an issue where components render twice without any apparent reason. This issue can be particularly perplexing, especially when the rendered data is seemingly correct on the second render.

Case Study: Phone Number Search Component Rendering Twice

In a specific case, a developer encountered this issue in a React component responsible for searching for points associated with a phone number pulled from URL parameters. The component rendered twice: the first render displayed only the phone number with zero points, while the second render displayed all data correctly.

Solution: Strict Mode Debugging

Upon examining the component's source code provided by the developer, it became evident that the component was running in React's Strict Mode. This mode intentionally triggers a double-invocation of the render function in development environments to help detect potential side effects during the render process.

Disabling Strict Mode

To resolve the issue, the developer commented out the strict mode tags in the index.js file of their app. This effectively disabled Strict Mode, leading to a single, expected render of the component.

React.StrictMode: Purpose and Effects

While Strict Mode can be useful for debugging side effects, it is crucial to understand its behavior. It operates solely in development mode and triggers double-invokes of the render function to help identify any inadvertent side effects.

Refer to the official React documentation for further insights into potential side effects that might lead to additional renders in React.StrictMode:

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

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