Andrew Clark
ddc91af795
An infinite update loop can occur when an update is scheduled inside a lifecycle method, which causes a re-render, which schedules another update, and so on. Before the Fiber rewrite, this scenario resulted in a stack overflow. Because Fiber does not use the JavaScript stack, we maintain our own counter to track the number of nested, synchronous updates. We throw an error if the limit is exceeded. The nested update limit is currently 1000. I chose this number arbitrarily, certain that there was no valid reason for a component to schedule so many synchronous re-renders. I think we can go much lower. This commit decreases the limit to 50. I believe this is still comfortably above the reasonable number of synchronous re-renders a component may perform. This will make it easier for developers to debug infinite update bugs when they occur.
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!