Common topics and questions you may encounter during a React.js interview

1. - React.js basics: You should have a good understanding of the React.js framework, including components, props, state, and the virtual DOM.
2. - JavaScript fundamentals: React.js is built on top of JavaScript, so it's important to have a solid understanding of JavaScript fundamentals such as variable scoping, closures, and asynchronous programming.
3. - CSS and HTML: Understanding the basics of HTML and CSS will be helpful when working with React.js, particularly when styling components.
4. - Redux: Redux is a popular state management library used with React.js. You may be asked about the basics of Redux, including actions, reducers, and the store.
5. - React Router: React Router is a library that allows you to handle routing in a React.js application. Be familiar with how React Router works and how to set up routes.
6. - Hooks: React.js Hooks are a way to use state and other React features without writing a class. You should know the basic Hooks, such as useState and useEffect.
7. - Best practices: You may be asked about best practices when working with React.js, such as code organization, performance optimization, and accessibility.