useContext in React

// Create context
const ThemeContext = createContext()

// Provider component
<ThemeContext.Provider value={{ dark: true }}>
  <App />
</ThemeContext.Provider>

// React 19: render <Context> directly as the provider
<ThemeContext value={{ dark: true }}>
  <App />
</ThemeContext>

// Consume in any child
const theme = useContext(ThemeContext)

// React 19: use() can read context conditionally (inside if/loops)
const theme2 = use(ThemeContext)

// Custom hook pattern
function useTheme() {
  const context = useContext(ThemeContext)
  if (!context) throw new Error('No ThemeProvider')
  return context
}