React Tips: Don't Add useForm Instance to useEffect Dependency Array

The Error

When you try to reset a form (using a useForm instance) inside a useEffect:

useEffect(() => {
  if (imageData?.imageUrl) {
    setImage(imageData.imageUrl);
    form.reset({});
  }
}, [imageData, form]);

you might encounter the following error:

Error Message: Uncaught Error: Maximum update depth exceeded. This can happen when a component repeatedly calls setState inside componentWillUpdate or componentDidUpdate. React limits the number of nested updates to prevent infinite loops.

Why Does This Happen?

The issue stems from how React manages dependencies in hooks and how useForm behaves:

1. New Instance on Every Render The useForm hook creates a new form instance every time the component renders. Its reference changes even if the state of the form remains the same.
2. Dependency Array Behavior React compares dependencies in the useEffect dependency array using shallow reference comparison. A new form instance on each render triggers the useEffect repeatedly, leading to an infinite loop.

How to Fix

1. Ignore the Warning with Comment

   useEffect(() => {
     if (imageData?.imageUrl) {
       setImage(imageData.imageUrl);
       form.reset({});
     }
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [imageData]);
   

2. Use a Ref for form.reset

   const resetRef = useRef(form.reset);
   
   useEffect(() => {
     if (imageData?.imageUrl) {
       setImage(imageData.imageUrl);
       resetRef.current({}); // Use ref for `reset`
     }
   }, [imageData]);
   

Conclusion

This issue highlights the importance of understanding how dependencies in hooks are evaluated. When working with libraries like react-hook-form, it’s crucial to avoid passing dynamic references like a useForm instance to the useEffect dependency array. Instead, use techniques like ignoring the dependency warning or utilizing refs to ensure stable references.

By applying these solutions, you can avoid infinite re-renders and ensure a smooth form handling experience in React.