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Juan
545d4c2de7
## Summary This commit is a proposal for handling duplicate installation of DevTools, in particular scoped to duplicates such as a dev build or the internal versions of DevTools installed alongside the Chrome Web Store extension. Specifically, this commit makes it so when another instance of the DevTools extension is installed alongside the extension installed from the Chrome Web Store, we don't produce a stream of errors or crash Chrome, which is what would usually happen in this case. ### Detecting Duplicate Installations - First, we check what type of installation the extension is: from the Chrome Web Store, the internal build of the extension, or a local development build. - If the extension is from the **Chrome Web Store**: - During initialization, we first check if the internal or local builds of the extension have already been installed and are enabled. To do this, we send a [cross-extension message](https://developer.chrome.com/docs/extensions/mv3/messaging/#external) to the internal and local builds of the extension using their extension IDs. - We can do this because the extension ID for the internal build (and for the Chrome Web Store) is a stable ID. - For the local build, at build time we hardcode a [`key` in the `manifest.json`](https://developer.chrome.com/docs/extensions/mv2/manifest/key/) which allows us to have a stable ID even for local builds. - If we detect that the internal or local extensions are already installed, then we skip initializing the current extension altogether so as to not conflict with the other versions. This means we don't initialize the frontend or the backend at all. - If the extension is the **Internal Build**: - During initialization, we first check if the local builds of the extension has already been installed and is enabled. To do this, we send a [cross-extension message](https://developer.chrome.com/docs/extensions/mv3/messaging/#external) to the local build of the extension using its extension ID. - We can do this for the local build because at build time we hardcode a [`key` in the `manifest.json`](https://developer.chrome.com/docs/extensions/mv2/manifest/key/) which allows us to have a stable ID even for local builds. - If we detect that the local extension is already installed, then we skip initializing the current extension altogether so as to not conflict with the that version. This means we don't initialize the frontend or the backend at all. - If the extension is a **Local Dev Build**: - Since other extensions check for the existence of this extension and disable themselves if they detect it, we don't need any special handling during initialization and assume that there are no duplicate extensions. This means that we will generally prefer keeping this extension enabled. This behavior means that the order of priority for keeping an extension enabled is the following: 1. Local build 2. Internal build 3. Public build ### Preventing duplicate backend initialization Note that the backend is injected and initialized by the content script listening to a message posted to the inspected window (via `postMessage`). Since the content script will be injected twice, once each by each instance of the extension, even if we initialize the extension once, both content scripts would still receive the single message posted from the single frontend, and it would then still inject and initialize the backend twice. In order to prevent this, we also add the extension ID to the message for injecting the backend. That way each content script can check if the message comes from its own extension, and if not it can ignore the message and avoid double injecting the backend. ### Other approaches - I considered using the [`chrome.management`](https://developer.chrome.com/docs/extensions/reference/management/) API generally to detect other installations, but that requires adding additional permissions to our production extension, which didn't seem ideal. - I also considered a few options of writing a special flag to the inspected window and checking for it before initializing the extension. However, it's hard to avoid race conditions in that case, and it seemed more reliable to check specifically for the WebStore extension, which is realistically where we would encounter the overlap. ### Rollout - This commit needs to be published and rolled out to the Chrome Web Store first. - After this commit is published to the Chrome Web Store, any duplicate instances of the extension that are built and installed after this commit will no longer conflict with the Chrome Web Store version. ### Next Steps - In a subsequent PR, I will extend this code to show a warning when duplicate extensions have been detected. Part of #22486 ## How did you test this change? ### Basic Testing - yarn flow - yarn test - yarn test-build-devtools ### Double installation testing Testing double-installed extensions for this commit is tricky because we are relying on the extension ID of the internal and Chrome Web Store extensions, but we obviously can't actually test the Web Store version (since we can't modify the already published version). In order to simulate duplicate extensions installed, I did the following process: - Built separate extensions where I hardcoded a constant for whether the extension is internal or public (e.g. `EXTENSION_INSTALLATION_TYPE = 'internal'`). Then I installed these built extensions corresponding to the "internal" and "Web Store" builds. - Build and run the regular development extension (with `yarn build:chrome:dev && yarn test:chrome`), using the extension IDs of the previously built extensions as the "internal" and "public" extension IDs. With this set up in place, I tested the following on pages both with and without React: - When only the local extension enabled, DevTools works normally. - When only the "internal" extension enabled, DevTools works normally. - When only the "public" extension enabled, DevTools works normally. - When "internal" and "public" extensions are installed, "public" extension is disabled and "internal" extension works normally. - When the local extension runs alongside the other extensions, other extensions disable themselves and local build works normally. - When we can't recognize what type of build the extension corresponds to, we show an error. - When all 3 extensions are installed and enabled in all different combinations, DevTools no longer produces errors or crashes Chrome, and works normally.
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 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 own 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 Online Playgrounds to get a taste of React.
- Add React to a Website as a
<script>tag in one minute. - Create a New React App if you're looking for a powerful JavaScript toolchain.
You can use React as a <script> tag from a CDN, or as a react package on npm.
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:
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:
function HelloMessage({ name }) {
return <div>Hello {name}</div>;
}
ReactDOM.render(
<HelloMessage name="Taylor" />,
document.getElementById('container')
);
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. If you're using React as a <script> tag, read this section on integrating JSX; otherwise, the recommended JavaScript toolchains handle it automatically.
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 which have a relatively limited scope. This is a great place to get started.
License
React is MIT licensed.