What is React.js?
React.js, commonly called React, is a JavaScript library used to build user interfaces. It is especially useful for applications where the screen needs to update when users interact with data.
React encourages developers to divide a large interface into smaller reusable components. For example, an e-commerce website can have Header, ProductCard, ProductList, Cart, and Checkout components.
Why Do We Need React?
Traditional JavaScript applications can become difficult to manage when many parts of a page need to change at the same time. React gives us a structured way to describe the UI and update it when application data changes.
- Reusable: Components can be used in many places.
- Declarative: You describe what the UI should look like for the current data.
- Component-based: Large applications can be divided into smaller pieces.
- Interactive: State and events make it easy to build dynamic interfaces.
Important React Idea
Think of a component as a function that receives data and returns UI. When its relevant inputs change, React can render the component again.
When Should You Learn React?
Before learning advanced React, you should understand basic HTML, CSS, JavaScript variables, functions, arrays, objects, conditions, loops, modules, and modern JavaScript syntax.