Theo's Typesafe Cult•10mo ago

Typescript errors with `cloneElement`

Hi all 👋 So while building my app I faced an issue that really put my UI at test. As I am sure many of you already experienced, the design of our application (even if we're the ones creating it) is able to account only for a small amount of cases. For example, I designed a card where the text can grow quite a lot and am figuring out the best approach. Specific to this request though is the fact that when I use the cloneElement and I try to set a new className I get the following error message: Argument of type '{ className: string; }' is not assignable to parameter of type 'Partial<unknown> & Attributes' Here's my code:

const massagedChildren = Array.isArray(children)
  ? children.map((child: ReactNode) => {
      if (!isValidElement(child)) return child;

      return cloneElement(child, {
        className: cn(child.props.className, { block: isOverflowing }),
      });
    })
  : null;

const massagedChildren = Array.isArray(children)
  ? children.map((child: ReactNode) => {
      if (!isValidElement(child)) return child;

      return cloneElement(child, {
        className: cn(child.props.className, { block: isOverflowing }),
      });
    })
  : null;

If you need I can give you more context about why this code it's useful for my app, but I don't think it's related with the issue. Thanks for the help 🙏 PS: that code also has an error for child.props.className because it gets inferred an any type for child even though I check with isValidElement just few lines above.

1 Reply

cupofcrypto•10mo ago

To whom would be interested in the future this is how I solved the errors. Not proud because I am not sure it is the best code, but at least it gets the job done.

// Made in order to solve some issues with `cloneElement`
type ChildrenProps = {
  className?: string;
};

children.map((child: ReactElement<ChildrenProps>) => {
  if (!isValidElement(child)) return child;

  return cloneElement(child as ReactElement, {
    className: cn(child.props.className as ClassValue, {
      block: isOverflowing,
    }),
  });
});

// Made in order to solve some issues with `cloneElement`
type ChildrenProps = {
  className?: string;
};

children.map((child: ReactElement<ChildrenProps>) => {
  if (!isValidElement(child)) return child;

  return cloneElement(child as ReactElement, {
    className: cn(child.props.className as ClassValue, {
      block: isOverflowing,
    }),
  });
});

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Typescript errors with `cloneElement`