React Fiber And Reconciliation

This article discusses React Fiber and Reconciliation, a fundamental algorithms in React

React Fiber is an internal implementation of the React reconciliation algorithm also it is a significant rewrite of the original reconciliation algorithm. Its purpose is to improve the performance and responsiveness of React applications. It achieves this by allowing the framework to pause and resume work, reorder priorities, and efficiently manage the rendering process. It was first introduced in React version 16.

Reconciliation

In React, reconciliation is the process of updating the user interface to reflect changes in the application state. React determines the necessary changes to the UI when the state of a component changes. The algorithmic process of reconciliation efficiently updates the DOM.

The process of reconciliation involves comparing the new virtual DOM representation of a component with its previous state and determining which changes (additions, updates, or removals) are necessary for the actual DOM. React aims to minimize the number of operations required to update the UI by using a diffing algorithm.

In my article about DOM Diff Algorithm, I discussed this issue in detail previously :)

Okay, lets continue...

React Fiber's main goal is to enable incremental rendering. This allows React to render a part of the UI without blocking the main thread, resulting in a better user experience and smoother interactions.

Fiber allows React to pause rendering work at any point and resume it later. This is especially useful for time-slicing and working on high-priority updates without blocking the main thread for too long.

React Fiber offers improved error boundary support, making it easier to catch and handle errors at the component level without crashing the entire application.

React Fiber's reconciliation process operates on a tree structure known as the Fiber tree. Each fiber represents a unit of work, and the tree structure reflects the component hierarchy in the React application.

Example: Before React Fiber

If the 'items' prop is changed, React will perform a full reconciliation. This involves creating a new virtual DOM tree, comparing it with the previous one, and updating the entire list in the DOM, even if only one item has been modified.

With React Fiber

React Fiber breaks down the rendering process into smaller units called fibers. When the items prop changes, React can incrementally render and update the list in smaller chunks, without blocking the main thread.

This results in a more responsive UI, particularly when dealing with dynamic and frequently changing data.

In summary, React Fiber is important because it enhances the performance and capabilities of React, making it more adaptable to the demands of modern web applications. It provides a foundation for incremental rendering, prioritization, and concurrent processing, leading to a more efficient and responsive development experience.

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