How do I run a Reactjs code?

js. To get an overview of what React is, you can write React code directly in HTML . But in order to use React in production, you need npm and Node.

You can put any valid JavaScript expression inside the curly braces in JSX . For example, 2 + 2 , user. firstName , or formatName(user) are all valid JavaScript expressions. In the example below, we embed the result of calling a JavaScript function, formatName(user) , into an <h1> element.

Using the create-react-app command