errorObj: unknown Object is of type 'unknown'-CodePudding

I am getting the error while using async, await in useEffect hook.

useEffect(() => {
if (contentLoader) {
      (async () => {
        try {
          const data = await promise;
          setData(data);
        } catch (errorObj) {
          if (!errorObj?.value) { //here i'm getting --> errorObj: unknown Object is of type 'unknown'.
            setError(errorObj);
            console.log(`loading document error: ${errorObj}`);
          }
        }
      })();
    } else // something else
}, [..])

whats wrong in my code.

CodePudding user response：

You're using TypeScript 4.4 or newer with [use-unknown-catch-variables] (https://devblogs.microsoft.com/typescript/announcing-typescript-4-4/#use-unknown-catch-variables) enabled.

The easiest fix, if you don't know the actual type of the error thrown, is to just tell TypeScript that it's any, not unknown.

catch (errorObj) {

catch (errorObj: any) {

CodePudding user response：

In TypeScript, catch clause variables may not have a type annotation (aside from, as of TypeScript 4.0, unknown). This is not specific to async. Using TypeScript to infer your custom error type:

interface ApiError {
  code: number;
  error: string;
}

Now

const isApiError = (x: any): x is ApiError => {
    return typeof x.code === 'number';
  };

useEffect(() => {
if (contentLoader) {
  (async () => {
    try {
      const data = await promise;
      setData(data);
    } catch (errorObj) {
     catch (error) {
     if (isApiError(errorObj)) {
       console.log(errorObj)
      }
    }
  })();
 } else // something else
 }, [..])