## Summary This PR improves the Trace Updates feature by letting developers see component names directly on the update overlay. Before this change, the overlay only highlighted updated regions, leaving it unclear which components were involved. With this update, you can now match visual updates to their corresponding components, making it much easier to debug rendering performance. ### New Feature: Show component names while highlighting When the new **"Show component names while highlighting"** setting is enabled, the update overlay display the names of affected components above the rectangles, along with the update count. This gives immediate context about what’s rendering and why. The preference is stored in local storage and synced with the backend, so it’s remembered across sessions. ### Improvements to Drawing Logic The drawing logic has been updated to make the overlay sharper and easier to read. Overlay now respect device pixel ratios, so they look great on high-DPI screens. Outlines have also been made crisper, which makes it easier to spot exactly where updates are happening. > [!NOTE] > **Grouping Logic and Limitations** > Updates are grouped by their screen position `(left, top coordinates)` to combine overlapping or nearby regions into a single group. Groups are sorted by the highest update count within each group, making the most frequently updated components stand out. > Overlapping labels may still occur when multiple updates involve components that overlap but are not in the exact same position. This is intentional, as the logic aims to maintain a straightforward mapping between update regions and component names without introducing unnecessary complexity. ### Testing This PR also adds tests for the new `groupAndSortNodes` utility, which handles the logic for grouping and sorting updates. The tests ensure the behavior is reliable across different scenarios. ## Before & After https://github.com/user-attachments/assets/6ea0fe3e-9354-44fa-95f3-9a867554f74c https://github.com/user-attachments/assets/32af4d98-92a5-47dd-a732-f05c2293e41b --------- Co-authored-by: Ruslan Lesiutin <rdlesyutin@gmail.com>
React ·

React is a JavaScript library for building user interfaces.
- Declarative: React makes it painless to create interactive UIs. Design simple views for each state in your application, and React will efficiently update and render just the right components when your data changes. Declarative views make your code more predictable, simpler to understand, and easier to debug.
- Component-Based: Build encapsulated components that manage their own state, then compose them to make complex UIs. Since component logic is written in JavaScript instead of templates, you can easily pass rich data through your app and keep the state out of the DOM.
- Learn Once, Write Anywhere: We don't make assumptions about the rest of your technology stack, so you can develop new features in React without rewriting existing code. React can also render on the server using Node and power mobile apps using React Native.
Learn how to use React in your project.
Installation
React has been designed for gradual adoption from the start, and you can use as little or as much React as you need:
- Use Quick Start to get a taste of React.
- Add React to an Existing Project to use as little or as much React as you need.
- Create a New React App if you're looking for a powerful JavaScript toolchain.
Documentation
You can find the React documentation on the website.
Check out the Getting Started page for a quick overview.
The documentation is divided into several sections:
- Quick Start
- Tutorial
- Thinking in React
- Installation
- Describing the UI
- Adding Interactivity
- Managing State
- Advanced Guides
- API Reference
- Where to Get Support
- Contributing Guide
You can improve it by sending pull requests to this repository.
Examples
We have several examples on the website. Here is the first one to get you started:
import { createRoot } from 'react-dom/client';
function HelloMessage({ name }) {
return <div>Hello {name}</div>;
}
const root = createRoot(document.getElementById('container'));
root.render(<HelloMessage name="Taylor" />);
This example will render "Hello Taylor" into a container on the page.
You'll notice that we used an HTML-like syntax; we call it JSX. JSX is not required to use React, but it makes code more readable, and writing it feels like writing HTML.
Contributing
The main purpose of this repository is to continue evolving React core, making it faster and easier to use. Development of React happens in the open on GitHub, and we are grateful to the community for contributing bugfixes and improvements. Read below to learn how you can take part in improving React.
Code of Conduct
Facebook has adopted a Code of Conduct that we expect project participants to adhere to. Please read the full text so that you can understand what actions will and will not be tolerated.
Contributing Guide
Read our contributing guide to learn about our development process, how to propose bugfixes and improvements, and how to build and test your changes to React.
Good First Issues
To help you get your feet wet and get you familiar with our contribution process, we have a list of good first issues that contain bugs that have a relatively limited scope. This is a great place to get started.
License
React is MIT licensed.