Why the Shift from jQuery?
jQuery is excellent for imperative tasks—telling the browser how to change the DOM step-by-step. However, as applications grow, constantly managing the DOM becomes slow and error-prone.
Component-Based Architecture
Modern frameworks adopt a declarative approach. You describe what the UI should look like for a given state, and the framework handles the updates efficiently. This is done by breaking the UI into reusable, isolated pieces called components (like a button, a sidebar, or a navigation bar).
This approach makes applications easier to scale, test, and maintain.
The Virtual DOM (VDOM)
Frameworks like React use a Virtual DOM—an in-memory, lightweight copy of the actual browser DOM. When data changes, the framework first updates the VDOM. It then efficiently compares the previous VDOM state to the new state (a process called "diffing"). Finally, it applies only the necessary changes to the real browser DOM, drastically boosting performance.