Render method and Reconciliation

Before Reconciliation, render() method is called.

render() method in React is responsible for describing what the UI should look like based on the current state and props. When the render() method is called, it returns a Virtual DOM representation of the component's UI. The virtual DOM is a lightweight, in-memory representation of the actual DOM structure.

Before reconciliation, the render() method does the following:

1. Creation of Virtual DOM Elements: The render() method creates React elements (virtual DOM elements) that represent the structure of the UI. These elements are lightweight JavaScript objects that describe what should be rendered.

2. Props and State Handling: The render() method incorporates the current state and props into the virtual DOM elements. This allows the UI to reflect the latest data and be responsive to changes in state or props.

3. Component Composition: If the component has child components, the render() method is also responsible for rendering these child components by invoking their respective render() methods.

4. Pure Function: The render() method is expected to be a pure function, meaning it should not have side effects. It should only depend on the input (props and state) and return a description of what the UI should look like.

After the render() method completes, React uses the virtual DOM representation to perform the reconciliation process. During reconciliation, React compares the new virtual DOM with the previous one, identifies the changes, and it applies them to the real DOM in a batched manner for performance optimization.