Why Does My React Component Render Twice in Strict Mode?

React Component Rendering Twice in Strict Mode

In strict mode, React intentionally double-invokes component render functions to detect potential side effects. This behavior becomes apparent by rendering a component twice.

In the provided code example, the Update component renders twice because it is running in strict mode. When you comment out the strict mode tag in index.js, the issue resolves, and the component renders only once.

React.StrictMode is a development mode feature that helps identify accidental side effects in the render phase. It achieves this by replicating the render function, which can reveal issues that might otherwise go unnoticed.

According to the React documentation, unexpected side effects during rendering can be caused by:

• Calling Hooks outside of the component render function
• Reading from the DOM during render
• Accessing a ref passed to a component during render
• mutating the state within a render function
• triggering state changes on the parent component from within a component's render function

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