30秒学会 React 片段 – useMediaQuery

A hook that returns a value based on a media query.

• Check if window and window.matchMedia exist, return whenFalse if not.
• Use window.matchMedia() to match the given query, cast its matches property to a boolean and store in a state variable, match, using React.useState().
• Use React.useEffect() to add a listener for changes and to clean up the listeners after the hook is destroyed.
• Return either whenTrue or whenFalse based on the value of match.

代码实现

const useMediaQuery = (query, whenTrue, whenFalse) => {
  if (typeof window === 'undefined' || typeof window.matchMedia === 'undefined') return whenFalse;

  const mediaQuery = window.matchMedia(query);
  const [match, setMatch] = React.useState(!!mediaQuery.matches);

  React.useEffect(() => {    
    const handler = () => setMatch(!!mediaQuery.matches);
    mediaQuery.addListener(handler);
    return () => mediaQuery.removeListener(handler);
  }, []);

  return match ? whenTrue : whenFalse;
};

使用样例

const ResponsiveText = () => {
  const text = useMediaQuery(
    '(max-width: 400px)', 'Less than 400px wide', 'More than 400px wide'
  );

  return <span>{text}</span>;
}

ReactDOM.render(<ResponsiveText />, document.getElementById('root'));