Using React's useEffect to implement a mousedown event listener

Question

Using React's useEffect to implement a mousedown event listener

I created a modal that automatically closes when the user clicks outside of it.

method one - involves passing isModalOpened to update the state only if the modal is currently open.

const [isModalOpened, toggleModal] = useState(false);
const ref = useRef(null);

const clickOutside = (e) => {
  if (!ref.current.contains(e.target) && isModalOpened) {
     toggleModal(false);
  }
};

React.useEffect(() => {
  window.addEventListener('mousedown', clickOutside);

  return () => {
     window.removeEventListener('mousedown', clickOutside);
  };
}, [isModalOpened]);

method two - excludes isModalOpened from the dependency array.

const [isModalOpened, toggleModal] = useState(false);
const ref = useRef(null);

const clickOutside = (e) => {
  if (!ref.current.contains(e.target)) {
     toggleModal(false);
  }
};

React.useEffect(() => {
  window.addEventListener('mousedown', clickOutside);

  return () => {
     window.removeEventListener('mousedown', clickOutside);
  };
}, []);

Concern: Am I supposed to include isModalOpened in the dependency array or not?

javascript reactjs

Answer 1

Answer №1

There is no requirement for it.

This is because toggling the modal to the same false value does not trigger a re-render.

Therefore, there is no need to check the value of `isModalOpened` and consequently exclude the variable from your function, eliminating the dependency altogether.

Answer 2

There is no requirement for it.

This is because toggling the modal to the same false value does not trigger a re-render.

Therefore, there is no need to check the value of `isModalOpened` and consequently exclude the variable from your function, eliminating the dependency altogether.

Answer 3

Answer №2

Avoid passing the isModalOpen variable to the deep array as it will result in the effect removing and adding the listener unnecessarily.

Answer 4

Avoid passing the isModalOpen variable to the deep array as it will result in the effect removing and adding the listener unnecessarily.

Answer 5

Answer №3

One way to approach this situation is by running the hook every time the status of isModalOpened changes. This method involves removing the global listener when the modal closes. Another approach would be to trigger the hook when the component is either mounted or unmounted, ensuring that the global listener remains active throughout the lifecycle of the component.

The best choice between the two approaches depends on how you intend to utilize the component. If you plan to have the component mounted before opening the modal (thus starting with an initial state of false), the second option will constantly monitor the mousedown event from mounting until unmounting. However, if the component will only be mounted when the modal is open, it would be more appropriate to set the global listener only when the modal is indeed open.

In this scenario, the first approach is recommended.

*edit

It's worth noting that in your if statement, you can eliminate the need for checking the value of isModalOpened.

Answer 6

One way to approach this situation is by running the hook every time the status of isModalOpened changes. This method involves removing the global listener when the modal closes. Another approach would be to trigger the hook when the component is either mounted or unmounted, ensuring that the global listener remains active throughout the lifecycle of the component.

The best choice between the two approaches depends on how you intend to utilize the component. If you plan to have the component mounted before opening the modal (thus starting with an initial state of false), the second option will constantly monitor the mousedown event from mounting until unmounting. However, if the component will only be mounted when the modal is open, it would be more appropriate to set the global listener only when the modal is indeed open.

In this scenario, the first approach is recommended.

*edit

It's worth noting that in your if statement, you can eliminate the need for checking the value of isModalOpened.

Answer 7

Answer №4

In my opinion, a slight adjustment could be made to improve the approach in this scenario. I would recommend wrapping the clickOut function within useCallback, where the dependencies include toggleModal and ref. Additionally, make clickOut a dependency in the useEffect. By doing this, whenever there is a change in either the ref or toggleModal, a new reference for clickOut will be created. Consequently, if there is a new reference for clickOut, listeners will be reassigned in the useEffect. This not only prevents unnecessary creation of the clickOut function on each render but also optimizes rendering.

Based on my suggestion, your code should appear as follows:

const [isModalOpened, toggleModal] = useState(false);
const ref = useRef(null);

const clickOut = useCallback((e) => {
  if (!ref.current.contains(e.target) && isModalOpened) {
     toggleModal(false);
  }
}, [isModalOpened, ref]);

React.useEffect(() => {
  window.addEventListener('mousedown', clickOut);

  return () => {
     window.removeEventListener('mousedown', clickOut);
  };
}, [clickOut]);

Answer 8

In my opinion, a slight adjustment could be made to improve the approach in this scenario. I would recommend wrapping the clickOut function within useCallback, where the dependencies include toggleModal and ref. Additionally, make clickOut a dependency in the useEffect. By doing this, whenever there is a change in either the ref or toggleModal, a new reference for clickOut will be created. Consequently, if there is a new reference for clickOut, listeners will be reassigned in the useEffect. This not only prevents unnecessary creation of the clickOut function on each render but also optimizes rendering.

Based on my suggestion, your code should appear as follows:

const [isModalOpened, toggleModal] = useState(false);
const ref = useRef(null);

const clickOut = useCallback((e) => {
  if (!ref.current.contains(e.target) && isModalOpened) {
     toggleModal(false);
  }
}, [isModalOpened, ref]);

React.useEffect(() => {
  window.addEventListener('mousedown', clickOut);

  return () => {
     window.removeEventListener('mousedown', clickOut);
  };
}, [clickOut]);

Using React's useEffect to implement a mousedown event listener

Answer №1

Answer №2

Answer №3

Answer №4

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