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Use the method in React's function component addEventListener:

1. Set the ref attribute on the element.
2. Use the current attribute on the ref to access the element.
3. useEffectAdd event listeners in the hook .

import {useRef, useEffect} from 'react';

const App = () => {
  const ref = useRef(null);

  useEffect(() => {
    const handleClick = event => {
      console.log('Button clicked');
    };

    const element = ref.current;

    element.addEventListener('click', handleClick);

    return () => {
      element.removeEventListener('click', handleClick);
    };
  }, []);

  return (
    <div>
      <button ref={ref}>Click</button>
    </div>
  );
};

export default App;

We useEffectadded an event listener to the element in the hook of the functional component.

If you want to add an event listener to the window or document object, use the same method but don't include the ref.

useRef()The hook can be passed an initial value as an argument. The hook returns a mutable ref object whose .current property is initialized to the passed argument.

请注意, we have to access the current property of the ref object in order to access the button element on which we set the ref attribute.

When we pass a ref prop to an element, for example <div ref={myRef} />, React sets the properties of the ref object .currentto the corresponding DOM node.

We pass an empty dependenciesarray to useEffectthe hook, so it will only run when the component mounts.

We only want to call addEventListenerthe method once - when the component mounts.

useEffect(() => {
  const handleClick = event => {
    console.log('Button clicked');
  };

  const element = ref.current;

  element.addEventListener('click', handleClick);

  return () => {
    element.removeEventListener('click', handleClick);
  };
}, []);

We store a reference to the element in a variable and use addEventListenerthe method to add a click event listener to the button.

The method takes as its first argument the type of event to listen for, and as its second argument a function to be called when an event of the specified type occurs.

The function we useEffectreturn from the hook is called when the component unmounts.

We use removeEventListenerthe method to remove the event listener we registered previously.

The cleanup step is important because we want to make sure that we don't have any memory leaks in our application.