What is the main function of JavaScript in web development?

The main function of JavaScript in web development is to add interactivity to web pages. JavaScript enables developers to create dynamic user experiences by responding to user actions such as clicks, keyboard inputs, and form submissions. This interactivity can include features like animations, dynamic content updates, and interactive forms, which enhance the user experience and engagement on a website.

By utilizing JavaScript, developers can manipulate the Document Object Model (DOM) to change the structure and content of a web page in real-time, allowing for seamless interactions without the need for full page reloads. This capability makes JavaScript an essential component of modern web applications, contributing to the overall functionality and responsiveness that users expect.

In contrast, while styling web pages falls under the domain of CSS, server-side applications are primarily handled by languages like Node.js, Python, or PHP. Designing database structures is typically the realm of database management systems and involves different tools and languages, making JavaScript distinctively focused on the front-end interactivity of web pages.