Among the most popular libraries for JavaScript, React is a framework that allows you to create UI components. It’s easy to learn, and you can use it to build a variety of web applications. You can integrate it into your current web page or create a new one.

React is known for its scalability and ease of use. It is used by a number of established companies. It is also used by many startups. Some of the companies using React include Facebook, Instagram, Netflix, Uber Eats, and The New York Times.

Facebook uses React in its newsfeed, ads manager, and other internal structures. Using React in these structures has led to some notable performance improvements.

React uses a Virtual DOM to monitor the state of a component. It then finds the cheapest way to re-render the component. If a key has changed, React will destroy the previous component and re-render the new one. This avoids layout trashing and minimizes DOM changes.

React also uses conventions for the names of its props. Props are properties passed to the children of a component. They can be strings, numbers, or other React components.

When a component changes, React will use a setState method to re-render it (more information). This method uses the SyntheticEvent wrapper to replace the native Event interface.

You can also use the setState method to update a sub. For example, when a subscribe button is clicked, the sub will be updated with the value of the subscribed message. This can help minimize expensive data calculations.