Andrew Clark
43ffae2d17
* Suspending inside a constructor outside of strict mode Outside of strict mode, suspended components commit in an incomplete state, then are synchronously deleted in a subsequent commit. If a component suspends inside the constructor, it mounts without an instance. This breaks at least one invariant: during deletion, we assume that every mounted component has an instance, and check the instance for the existence of `componentWillUnmount`. Rather than add a redundant check to the deletion of every class component, components that suspend inside their constructor and outside of strict mode are turned into empty functional components before they are mounted. This is a bit weird, but it's an edge case, and the empty component will be synchronously unmounted regardless. * Do not fire lifecycles of a suspended component In non-strict mode, suspended components commit, but their lifecycles should not fire.
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
var Reconciler = require('react-reconciler');
var HostConfig = {
// You'll need to implement some methods here.
// See below for more information and examples.
};
var MyRenderer = Reconciler(HostConfig);
var 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:
var 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!