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react-lifecycles-compat
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Backwards compatibility polyfill for React class components
The react-lifecycles-compat npm package is designed to polyfill the new React lifecycle methods to work with older versions of React (versions 0.14.9 to 16.2). This allows developers to use new features of React like getDerivedStateFromProps and getSnapshotBeforeUpdate in their existing projects without needing to completely refactor their components for newer React versions.
Polyfill for getDerivedStateFromProps
This feature allows the use of getDerivedStateFromProps in components that are part of projects using older versions of React. The polyfill function modifies the component to use this lifecycle method correctly even if the React version originally does not support it.
import { polyfill } from 'react-lifecycles-compat';
class MyComponent extends React.Component {
static getDerivedStateFromProps(nextProps, prevState) {
if (nextProps.value !== prevState.value) {
return {
value: nextProps.value
};
}
return null;
}
}
polyfill(MyComponent);
export default MyComponent;
Polyfill for getSnapshotBeforeUpdate
This feature enables the use of getSnapshotBeforeUpdate, which is useful for capturing some information from the DOM before it is potentially changed due to updates. The polyfill ensures it can be used in older React versions.
import { polyfill } from 'react-lifecycles-compat';
class MyComponent extends React.Component {
getSnapshotBeforeUpdate(prevProps, prevState) {
if (prevProps.list.length < this.props.list.length) {
const listDiff = this.props.list.length - prevProps.list.length;
return { listDiff: listDiff };
}
return null;
}
componentDidUpdate(prevProps, prevState, snapshot) {
if (snapshot !== null) {
console.log('List length increased by', snapshot.listDiff);
}
}
}
polyfill(MyComponent);
export default MyComponent;
This package offers a set of components that manage lifecycle methods in a more declarative way. While it provides similar lifecycle management capabilities, it does not specifically target compatibility issues between different React versions like react-lifecycles-compat does.
React version 17 will deprecate several of the class component API lifecycles: componentWillMount
, componentWillReceiveProps
, and componentWillUpdate
. (Read the Update on Async rendering blog post to learn more about why.) A couple of new lifecycles are also being added to better support async rendering mode.
Typically, this type of change would require third party libraries to release a new major version in order to adhere to semver. However, the react-lifecycles-compat
polyfill offers a way to use the new lifecycles with older versions of React as well (0.14.9+) so no breaking release is required. This enables shared libraries to support both older and newer versions of React simultaneously.
First, install the polyfill from NPM:
# Yarn
yarn add react-lifecycles-compat
# NPM
npm install react-lifecycles-compat --save
Next, update your component and replace any of the deprecated lifecycles with new ones introduced with React 16.3. (Refer to the React docs for examples of how to use the new lifecycles.)
Lastly, use the polyfill to make the new lifecycles work with older versions of React:
import React from 'react';
import {polyfill} from 'react-lifecycles-compat';
class ExampleComponent extends React.Component {
static getDerivedStateFromProps(nextProps, prevState) {
// Normally this method would only work for React 16.3 and newer,
// But the polyfill will make it work for older versions also!
}
getSnapshotBeforeUpdate(prevProps, prevState) {
// Normally this method would only work for React 16.3 and newer,
// But the polyfill will make it work for older versions also!
}
// render() and other methods ...
}
// Polyfill your component so the new lifecycles will work with older versions of React:
polyfill(ExampleComponent);
export default ExampleComponent;
Currently, this polyfill supports static getDerivedStateFromProps
and getSnapshotBeforeUpdate
- both introduced in version 16.3.
Note that in order for the polyfill to work, none of the following lifecycles can be defined by your component: componentWillMount
, componentWillReceiveProps
, or componentWillUpdate
.
Note also that if your component contains getSnapshotBeforeUpdate
, componentDidUpdate
must be defined as well.
An error will be thrown if any of the above conditions are not met.
3.0.4 (May 11, 2018)
Fixed shallow renderer regression (introduced in 3.0.3) that caused setState
updater to fail due to incorrect this
. (#26)
FAQs
Backwards compatibility polyfill for React class components
We found that react-lifecycles-compat demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 7 open source maintainers collaborating on the project.
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