React useEffect hook with warning react-hooks/exhaustive-deps

Question

I am converting code that used componentDidMount/Update/Unmount lifecycle to React Hooks and keep coming up against react-hooks/exhaustive-deps in the console as a warning.

Our new code appears to work as intended and so my thoughts are to turn these warnings off. However, in case I have missed something, are the warnings warranted in the below code.

Old componentDidMount/Update/Unmount code

  state = {
    container: canUseDOM ? createContainer(this.props.zIndex) : undefined,
    portalIsMounted: false,
  };

  componentDidUpdate(prevProps: Props, prevState: State) {
    const { container } = this.state;
    const { zIndex } = this.props;
    if (container && prevProps.zIndex !== zIndex) {
      const newContainer = createContainer(zIndex);

      getPortalParent().replaceChild(container, newContainer);
      this.setState({ container: newContainer });
    } else if (!prevState.container && container) {
      getPortalParent().appendChild(container);
    }
  }

  componentDidMount() {
    const { container } = this.state;
    const { zIndex } = this.props;
    if (container) {
      getPortalParent().appendChild(container);
    } else {
      const newContainer = createContainer(zIndex);
      this.setState({ container: newContainer });
    }
    this.setState({
      portalIsMounted: true,
    });

    firePortalEvent(PORTAL_MOUNT_EVENT, Number(zIndex));
  }

  componentWillUnmount() {
    const { container } = this.state;
    const { zIndex } = this.props;
    if (container) {
      getPortalParent().removeChild(container);
      const portals = !!document.querySelector(
        'body > .portal-container > .portal',
      );
      if (!portals) {
        getBody().removeChild(getPortalParent());
      }
    }

    firePortalEvent(PORTAL_UNMOUNT_EVENT, Number(zIndex));
  }

New React Hooks code

const [container, setContainer] = useState(canUseDOM ? createContainer(zIndex) : undefined);
const [portalIsMounted, setPortalIsMounted] = useState(false);

  useEffect(() => {
    if (container) {
      const newContainer = createContainer(zIndex);
      getPortalParent().replaceWith(container, newContainer);
      setContainer(newContainer);
    }
  }, [zIndex]);

  useEffect(() => {
    if (container) {
      getPortalParent().appendChild(container);
    }
  }, [container]);

  useEffect(() => {
    if (container) {
      getPortalParent().appendChild(container);
    } else {
      const newContainer = createContainer(zIndex);
      setContainer(newContainer);
    }
    setPortalIsMounted(true);
    firePortalEvent(PORTAL_MOUNT_EVENT, Number(zIndex));
  }, []);

  useEffect(() => {
    if (container) {
      getPortalParent().removeChild(container);
      const portals = !!document.querySelector(
        'body > .portal-container > .portal'
      );
      if (!portals) {
        getBody().removeChild(getPortalParent());
      }
    }

    firePortalEvent(PORTAL_UNMOUNT_EVENT, Number(zIndex));
  }, []);

code for componentWillUnmount should be returned from useEffect callback — marzelin
– marzelin, Commented Oct 24, 2019 at 22:29

Willman.Codes · Accepted Answer · 2019-10-24 22:41:17Z

3

Here you use container in your useEffect, however since you are also setting container state in this effect you cannot put it as a dependency or else you will get an infinite loop (the effect will run every time setContainer is called).

I think this may be an acceptable time to use // eslint-disable-line

useEffect(() => {       
   if (container) {
      const newContainer = createContainer(zIndex);
      getPortalParent().replaceWith(container, newContainer);
      setContainer(newContainer);
   }
// eslint-disable-line
}, [zIndex]);

There may be other examples but you can figure out which useEffects require what dependancies.

edited Oct 24, 2019 at 22:41

answered Oct 24, 2019 at 22:36

Willman.Codes

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