Andrew Clark
eb3181e772
* Add Visibility flag for hiding/unhiding trees There's `beforeblur` logic in the snapshot phase that needs to visit every Suspense boundary whose visibility is toggled. Right now it does that by visiting Placement and Deletion effects. That includes many unrelated nodes. By adding a new flag specifically for toggling Visibility, we will only visit the relevant Suspense (and Offscreen) boundaries, instead of all nodes that have a Placement. Potential follow-ups (not urgent): - The `beforeblur` logic also has a check to see whether the visibility was toggled on or off. It only cares about things being hidden. As a follow up, I can split the Visibility flag into separate Hide/Show flags, and only visit Hide. - Now that this is separate from Update, we can move the rest of the Suspense's layout effects (like attaching retry listeners) to the passive phase. * Gate behind createEventHandle feature flag Only need to visit deleted and hidden trees during the snapshot phase if the experimental `createEventHandle` flag is enabled. Currently, it's only used internally at Facebook, not open source.
react-reconciler
This is an experimental package for creating custom React renderers.
Its API is not as stable as that of React, React Native, or React DOM, and does not follow the common versioning scheme.
Use it at your own risk.
API
const Reconciler = require('react-reconciler');
const HostConfig = {
// You'll need to implement some methods here.
// See below for more information and examples.
};
const MyRenderer = Reconciler(HostConfig);
const RendererPublicAPI = {
render(element, container, callback) {
// Call MyRenderer.updateContainer() to schedule changes on the roots.
// See ReactDOM, React Native, or React ART for practical examples.
}
};
module.exports = RendererPublicAPI;
Practical Examples
A "host config" is an object that you need to provide, and that describes how to make something happen in the "host" environment (e.g. DOM, canvas, console, or whatever your rendering target is). It looks like this:
const HostConfig = {
createInstance(type, props) {
// e.g. DOM renderer returns a DOM node
},
// ...
supportsMutation: true, // it works by mutating nodes
appendChild(parent, child) {
// e.g. DOM renderer would call .appendChild() here
},
// ...
};
For an introduction to writing a very simple custom renderer, check out this article series:
The full list of supported methods can be found here. For their signatures, we recommend looking at specific examples below.
The React repository includes several renderers. Each of them has its own host config.
The examples in the React repository are declared a bit differently than a third-party renderer would be. In particular, the HostConfig object mentioned above is never explicitly declared, and instead is a module in our code. However, its exports correspond directly to properties on a HostConfig object you'd need to declare in your code:
- React ART and its host config
- React DOM and its host config
- React Native and its host config
If these links break please file an issue and we’ll fix them. They intentionally link to the latest versions since the API is still evolving. If you have more questions please file an issue and we’ll try to help!