React useToggler hook

Provides a boolean state variable that can be toggled between its two states.

• Use the useState() hook to create the value state variable and its setter.
• Create a function that toggles the value of the value state variable and memoize it, using the useCallback() hook.
• Return the value state variable and the memoized toggler function.

const useToggler = initialState => {
  const [value, setValue] = React.useState(initialState);

  const toggleValue = React.useCallback(() => setValue(prev => !prev), []);

  return [value, toggleValue];
};

const Switch = () => {
  const [val, toggleVal] = useToggler(false);
  return <button onClick={toggleVal}>{val ? 'ON' : 'OFF'}</button>;
};
ReactDOM.render(<Switch />, document.getElementById('root'));