useContext - Docs

useContext is a hook that lets you get data from a React Context

// Calling signature
const contextValue = useContext(context)

Basic Usage

(() => {
  const themes = {
    light: {
      foreground: "#000000",
      background: "#eeeeee"
    },
    dark: {
      foreground: "#ffffff",
      background: "#222222"
    }
  };

  const ThemeContext = React.createContext(themes.light);

  function ThemedButton() {
    const theme = useContext(ThemeContext);
    return (
      <button style={{ background: theme.background, color: theme.foreground }}>
        I am styled by theme context!
      </button>
    );
  }

  function Toolbar(props) {
    return (
      <div>
        <ThemedButton />
      </div>
    );
  }

  function App() {
    return (
      <ThemeContext.Provider value={themes.dark}>
        <Toolbar />
      </ThemeContext.Provider>
    );
  }
  return App
})()