Polyfill for the proposed React context API
npm install @hypnosphi/create-react-context> Polyfill for the proposed React context API
``sh`
yarn add create-react-context
You'll need to also have react and prop-types installed.
`js`
const Context = createReactContext(defaultValue);
//
// ...
//
`js
// @flow
import React, { type Node } from 'react';
import createReactContext, { type Context } from 'create-react-context';
type Theme = 'light' | 'dark';
// Pass a default theme to ensure type correctness
const ThemeContext: Context
class ThemeToggler extends React.Component<
{ children: Node },
{ theme: Theme }
> {
state = { theme: 'light' };
render() {
return (
// Pass the current context value to the Provider's value prop.
// Changes are detected using strict comparison (Object.is)
onClick={() => {
this.setState(state => ({
theme: state.theme === 'light' ? 'dark' : 'light'
}));
}}
>
Toggle theme
{this.props.children}
);
}
}
class Title extends React.Component<{ children: Node }> {
render() {
return (
// The Consumer uses a render prop API. Avoids conflicts in the
// props namespace.
{theme => (
{this.props.children}
)}
);
}
}
`
This package only "ponyfills" the React.createContext API, not other
unrelated React 16+ APIs. If you are using a version of React <16, keep
in mind that you can only use features available in that version.
For example, you cannot pass children types aren't valid pre React 16:
`js`
It will throw A valid React element (or null) must be returned. You may have returned undefined, an array or some other invalid object. because can only receive a single child element. To fix the error just wrap everyting in a single :`js``