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Rendering User Interfaces (UI)

To understand how React works, we first need a basic understanding of how browsers interpret your code to create (or render) user interfaces (UI).

When a user visits a web page, the server returns an HTML file to the browser that may look like this:

Two side-by-side diagrams, left showing the HTML code, and right showing the DOM tree.

The browser then reads the HTML and constructs the Document Object Model (DOM).

What is the DOM?

The DOM is an object representation of the HTML elements. It acts as a bridge between your code and the user interface, and has a tree-like structure with parent and child relationships.

Two side-by-side diagrams, left showing the DOM tree, and right showing the rendered UI.

You can use DOM methods and JavaScript, to listen to user events and manipulate the DOM by selecting, adding, updating, and deleting specific elements in the user interface. DOM manipulation allows you to not only target specific elements, but also change their style and content.

In the next section you'll learn how to use JavaScript and DOM methods.

Additional Resources:

You've Completed Chapter 2

You should now understand the fundamentals of how UI is rendered on the browser.

Next Up

3: Updating UI with Javascript

Learn how developers use JavaScript to manipulate the DOM and update the UI.