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Summary: We used to have Event Replaying for any kind of Discrete event where we'd track any event after hydrateRoot and before the async code/data has loaded in to hydrate the target. However, this didn't really work out because code inside event handlers are expected to be able to synchronously read the state of the world at the time they're invoked. If we replay discrete events later, the mutable state around them like selection or form state etc. may have changed. This limitation doesn't apply to Client Actions: - They're expected to be async functions that themselves work asynchronously. They're conceptually also in the "navigation" events that happen after the "submit" events so they're already not synchronously even before the first `await`. - They're expected to operate mostly on the FormData as input which we can snapshot at the time of the event. This PR adds a bit of inline script to the Fizz runtime (or external runtime) to track any early submit events on the page - but only if the action URL is our placeholder `javascript:` URL. We track a queue of these on `document.$$reactFormReplay`. Then we replay them in order as they get hydrated and we get a handle on the Client Action function. I add the runtime to the `bootstrapScripts` phase in Fizz which is really technically a little too late, because on a large page, it might take a while to get to that script even if you have displayed the form. However, that's also true for external runtime. So there's a very short window we might miss an event but it's good enough and better than risking blocking display on this script. The main thing that makes the replaying difficult to reason about is that we can have multiple instance of React using this same queue. This would be very usual but you could have two different Reacts SSR:ing different parts of the tree and using around the same version. We don't have any coordinating ids for this. We could stash something on the form perhaps but given our current structure it's more difficult to get to the form instance in the commit phase and a naive solution wouldn't preserve ordering between forms. This solution isn't 100% guaranteed to preserve ordering between different React instances neither but should be in order within one instance which is the common case. The hard part is that we don't know what instance something will belong to until it hydrates. So to solve that I keep everything in the original queue while we wait, so that ordering is preserved until we know which instance it'll go into. I ended up doing a bunch of clever tricks to make this work. These could use a lot more tests than I have right now. Another thing that's tricky is that you can update the action before it's replayed but we actually want to invoke the old action if that happens. So we have to extract it even if we can't invoke it right now just so we get the one that was there during hydration. DiffTrain build for commit https://github.com/facebook/react/commit/bf449ee74e5e98af3d08c87bb6a9f22a021f3522. Changelog: [Internal] Reviewed By: poteto Differential Revision: D45274088 Pulled By: kassens fbshipit-source-id: 7e9d96731f0bc72ea5fa3ffc6ce3f4a1dfe80d90
React Native
Learn once, write anywhere:
Build mobile apps with React.
Getting Started · Learn the Basics · Showcase · Contribute · Community · Support
React Native brings React's declarative UI framework to iOS and Android. With React Native, you use native UI controls and have full access to the native platform.
- Declarative. React makes it painless to create interactive UIs. Declarative views make your code more predictable and easier to debug.
- Component-Based. Build encapsulated components that manage their state, then compose them to make complex UIs.
- Developer Velocity. See local changes in seconds. Changes to JavaScript code can be live reloaded without rebuilding the native app.
- Portability. Reuse code across iOS, Android, and other platforms.
React Native is developed and supported by many companies and individual core contributors. Find out more in our ecosystem overview.
Contents
- Requirements
- Building your first React Native app
- Documentation
- Upgrading
- How to Contribute
- Code of Conduct
- License
📋 Requirements
React Native apps may target iOS 12.4 and Android 5.0 (API 21) or newer. You may use Windows, macOS, or Linux as your development operating system, though building and running iOS apps is limited to macOS. Tools like Expo can be used to work around this.
🎉 Building your first React Native app
Follow the Getting Started guide. The recommended way to install React Native depends on your project. Here you can find short guides for the most common scenarios:
📖 Documentation
The full documentation for React Native can be found on our website.
The React Native documentation discusses components, APIs, and topics that are specific to React Native. For further documentation on the React API that is shared between React Native and React DOM, refer to the React documentation.
The source for the React Native documentation and website is hosted on a separate repo, @facebook/react-native-website.
🚀 Upgrading
Upgrading to new versions of React Native may give you access to more APIs, views, developer tools, and other goodies. See the Upgrading Guide for instructions.
React Native releases are discussed in this discussion repo.
👏 How to Contribute
The main purpose of this repository is to continue evolving React Native core. We want to make contributing to this project as easy and transparent as possible, and we are grateful to the community for contributing bug fixes and improvements. Read below to learn how you can take part in improving React Native.
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 Native.
Open Source Roadmap
You can learn more about our vision for React Native in the Roadmap.
Good First Issues
We have a list of good first issues that contain bugs which have a relatively limited scope. This is a great place to get started, gain experience, and get familiar with our contribution process.
Discussions
Larger discussions and proposals are discussed in @react-native-community/discussions-and-proposals.
📄 License
React Native is MIT licensed, as found in the LICENSE file.
React Native documentation is Creative Commons licensed, as found in the LICENSE-docs file.