Josh Story
63310df2b2
Historically React would produce component stacks for dev builds only. There is a cost to tracking component stacks and given the prod builds try to optimize runtime performance these stacks were left out. More recently React added production component stacks to Fiber in because it can be immensely helpful in tracking down hard to debug production issues. Fizz was not updated to have a similar behavior. With the advent of prerendering however stacks for production in Fizz are more relevant because prerendering is not really a dev-time task. If you want the ability to reason about errors or postpones that happen during a prerender having component stacks to interrogate is helpful and these component stacks need to be available in production otherwise you are really never going to see them. (it is possible that you could do dev-mode prerenders but we don't expect this to be a common dev mode workflow) To better support the prerender use case and to make error logging in Fizz more useful the following changes have been made 1. `onPostpone` now accepts a second `postponeInfo` argument which will contain a componentStack. Postpones always originate from a component render so the stack should be consistently available. The type however will indicate the stack is optional so we can remove them in the future if we decide the overhead is the wrong tradeoff in certain cases 2. `onError` now accepts a second `errorInfo` argument which may contain a componentStack. If an error originated from a component a stack will be included in the following cases. This change entails tracking the component hierarchy in prod builds now. While this isn't cost free it is implemented in a relatively lean manner. Deferring the most expensive work (reifying the stack) until we are actually in an error pathway. In the course of implementing this change a number of simplifications were made to the code which should make the stack tracking more resilient. We no longer use a module global to curry the stack up to some handler. This was delicate because you needed to always reset it properly. We now curry the stack on the task itself. Another change made was to track the component stack on SuspenseBoundary instances so that we can provide the stack when aborting suspense boundaries to help you determine which ones were affected by an abort.
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
- Manging 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.