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Along with all the places using it like the `_debugSource` on Fiber. This still lets them be passed into `createElement` (and JSX dev runtime) since those can still be used in existing already compiled code and we don't want that to start spreading to DOM attributes. We used to have a DEV mode that compiles the source location of JSX into the compiled output. This was nice because we could get the actual call site of the JSX (instead of just somewhere in the component). It had a bunch of issues though: - It only works with JSX. - The way this source location is compiled is different in all the pipelines along the way. It relies on this transform being first and the source location we want to extract but it doesn't get preserved along source maps and don't have a way to be connected to the source hosted by the source maps. Ideally it should just use the mechanism other source maps use. - Since it's expensive it only works in DEV so if it's used for component stacks it would vary between dev and prod. - It only captures the callsite of the JSX and not the stack between the component and that callsite. In the happy case it's in the component but not always. Instead, we have another zero-cost trick to extract the call site of each component lazily only if it's needed. This ensures that component stacks are the same in DEV and PROD. At the cost of worse line number information. The better way to get the JSX call site would be to get it from `new Error()` or `console.createTask()` inside the JSX runtime which can capture the whole stack in a consistent way with other source mappings. We might explore that in the future. This removes source location info from React DevTools and React Native Inspector. The "jump to source code" feature or inspection can be made lazy instead by invoking the lazy component stack frame generation. That way it can be made to work in prod too. The filtering based on file path is a bit trickier. When redesigned this UI should ideally also account for more than one stack frame. With this change the DEV only Babel transforms are effectively deprecated since they're not necessary for anything.
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.