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// eslint-disable-next-line no-unused-vars
import { createElement, Component, createContext, Fragment } from 'preact';
const { Provider, Consumer } = createContext();
class ThemeProvider extends Component {
state = {
value: this.props.value
};
onClick = () => {
this.setState(prev => ({
value:
prev.value === this.props.value ? this.props.next : this.props.value
}));
};
render() {
return (
<div>
<button onClick={this.onClick}>Toggle</button>
<Provider value={this.state.value}>{this.props.children}</Provider>
</div>
);
}
}
class Child extends Component {
shouldComponentUpdate() {
return false;
}
render() {
return (
<>
<p>(blocked update)</p>
{this.props.children}
</>
);
}
}
export default class ContextDemo extends Component {
render() {
return (
<ThemeProvider value="blue" next="red">
<Child>
<Consumer>
{data => (
<div>
<p>
current theme: <b>{data}</b>
</p>
<ThemeProvider value="black" next="white">
<Consumer>
{data => (
<p>
current sub theme: <b>{data}</b>
</p>
)}
</Consumer>
</ThemeProvider>
</div>
)}
</Consumer>
</Child>
</ThemeProvider>
);
}
}
|
