استخدام السياق (Context)

class App extends React.Component {
  render() {
    return <Toolbar theme="dark" />;
  }
}

function Toolbar(props) {
  // The Toolbar component must take an extra "theme" prop  // and pass it to the ThemedButton. This can become painful  // if every single button in the app needs to know the theme  // because it would have to be passed through all components.  return (
    <div>
      <ThemedButton theme={props.theme} />    </div>
  );
}

class ThemedButton extends React.Component {
  render() {
    return <Button theme={this.props.theme} />;
  }
}

// Context lets us pass a value deep into the component tree// without explicitly threading it through every component.// Create a context for the current theme (with "light" as the default).const ThemeContext = React.createContext('light');
class App extends React.Component {
  render() {
    // Use a Provider to pass the current theme to the tree below.    // Any component can read it, no matter how deep it is.    // In this example, we're passing "dark" as the current value.    return (
      <ThemeContext.Provider value="dark">        <Toolbar />
      </ThemeContext.Provider>
    );
  }
}

// A component in the middle doesn't have to// pass the theme down explicitly anymore.function Toolbar() {
  return (
    <div>
      <ThemedButton />
    </div>
  );
}

class ThemedButton extends React.Component {
  // Assign a contextType to read the current theme context.  // React will find the closest theme Provider above and use its value.  // In this example, the current theme is "dark".  static contextType = ThemeContext;
  render() {
    return <Button theme={this.context} />;  }
}