Explain Strict Mode in React js

Strict Mode in React.js is a development mode that enforces strict checks to identify potential issues and deprecated code patterns, aiding in improving code quality and preparing applications for future updates by highlighting warnings or errors during development.

To enable Strict Mode in a React application, you can wrap your entire application or specific components with <React.StrictMode> component. For example:

import React from 'react';

const App = () => {
  return (
    <React.StrictMode>
      {/* Your entire application components go here */}
    </React.StrictMode>
  );
};

export default App;

When Strict Mode is enabled, React will perform additional checks and warnings during development to help identify potential issues. Some of the behaviors introduced by Strict Mode include:

1. Identifying Unsafe Lifecycles: Strict Mode will highlight components with unsafe lifecycles, such as those using componentWillMount, componentWillUpdate, and componentWillReceiveProps. These lifecycle methods are considered deprecated, and their usage can lead to bugs.

2. Detecting Legacy String Refs: Strict Mode helps detect the usage of string refs, which are considered legacy. It encourages using callback refs instead.

3. Warning about Deprecated FindDOMNode: Strict Mode will warn if findDOMNode is used to find the DOM node of a component. This method is deprecated, and its usage is discouraged.

4. Detecting Unexpected Side Effects: Strict Mode helps identify side effects in functions passed to setState and useEffect that may not be obvious. It helps catch unintended behavior that might lead to bugs.

It's important to note that Strict Mode checks are only active in the development environment and do not impact the production build. The purpose of Strict Mode is to provide additional assistance during development to improve code quality and catch potential issues early in the development process. Once the application is ready for production, Strict Mode can be removed without affecting the production build.