[jira] [Created] (ARROW-4442) [JS] Overly broad type annotation for Chunked typeId leading to type mismatches in generated typing

["Paul Taylor (JIRA)" <ji...@apache.org>]

Paul Taylor created ARROW-4442:
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             Summary: [JS] Overly broad type annotation for Chunked typeId leading to type mismatches in generated typing
                 Key: ARROW-4442
                 URL: https://issues.apache.org/jira/browse/ARROW-4442
             Project: Apache Arrow
          Issue Type: Improvement
          Components: JavaScript
    Affects Versions: 0.4.0
            Reporter: Paul Taylor
            Assignee: Paul Taylor


Typescript is generating an overly broad type for the `typeId` property of the ChunkedVector class, leading to a type mismatch and failure to infer Column<T> is Vector<T>:


{code:actionscript}

let col: Vector<Utf8>;
col = new Chunked(new Utf8());
  ^
/*
Argument of type 'Chunked<Utf8>' is not assignable to parameter of type 'Vector<Utf8>'.
  Type 'Chunked<Utf8>' is not assignable to type 'Vector<Utf8>'.
    Types of property 'typeId' are incompatible.
      Type 'Type' is not assignable to type 'Type.Utf8'.
*/
{code}

The fix is to add an explicit return annotation to the Chunked typeId getter.



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