React forwardRef with typescript

Question

I have forwarded ref using React forwardRef below is my code:

interface PropsDummy {}

const ProfileMenu = forwardRef<HTMLInputElement, PropsDummy>((props, ref) => {
  console.log(ref.current);
}

but why this causing typescript error?

Property 'current' does not exist on type '((instance: HTMLInputElement | null) => void) | MutableRefObject<HTMLInputElement | null>'

but if I use aliasing that current object works great without typescript error

interface PropsDummy {}

const ProfileMenu = forwardRef<HTMLInputElement, PropsDummy>((props, ref) => {
  const myRef = ref as React.RefObject<HTMLInputElement>;
  console.log(myRef.current);
}

how to get current object without typescript error?

thanks

Answer 1

The reason it doesn't work is because the type for ForwardedRef is defined as:

type ForwardedRef<T> = ((instance: T | null) => void) | MutableRefObject<T | null> | null;

Or in this particular case:

((instance: HTMLInputElement | null) => void) | MutableRefObject<HTMLInputElement | null>

Attempting to just access .current, without doing some type checking won't work because as you can see, the ref could be a function and functions do not have such a property (current).

It worked when you cast the object to your expected type, but note that refs can be either a function or an object (or null!), so you should be checking for this before attempting to access the current property.

This should work:

const ProfileMenu = forwardRef<HTMLInputElement, PropsDummy>((props, forwardedRef) => {
  if (forwardedRef != null && typeof forwardedRef !== 'function') {
    console.log(forwardedRef.current);
  }
  
  return (
    <div className="App" ref={forwardedRef}>
      <h1>Hello there</h1>
    </div>
  );
});