reactjs / reactjs/react-docgen

TypeScript: Missing Union Elements of Indexed Access Type

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typescript
Dominant language
TypeScript
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Avg merge
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Merged PRs (30d)
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Description

Hello there,
In the following code, the elements of the size props are not outputted.

type Base = {
  size: "small" | "medium" | "large";  
};

type Props = {
  size: Base["size"];
}

const MyComponent = ({size}: Props) => {
  return <div />;
}

Result

[
  {
    "description": "",
    "displayName": "MyComponent",
    "methods": [],
    "props": {
      "size": {
        "required": true,
        "tsType": {
          "name": "union",
          "raw": "Base[\"size\"]"
        },
        "description": ""
      }
    }
  }
]

Expected Behavior

[
  {
    "description": "",
    "displayName": "MyComponent",
    "methods": [],
    "props": {
      "size": {
        "required": true,
        "tsType": {
          "name": "union",
          "raw": "\"small\" | \"medium\" | \"large\"",
          "elements": [
            {
              "name": "literal",
              "value": "\"small\""
            },
            {
              "name": "literal",
              "value": "\"medium\""
            },
            {
              "name": "literal",
              "value": "\"large\""
            }
          ]
        },
        "description": ""
      }
    }
  }
]

I reproduced it here:
https://react-docgen.dev/playground

Thanks for regards.

Contributor guide

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First steps

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the TypeScript example in the issue and reproduce it in the react-docgen playground. Trace how the indexed-access type is handled, then add coverage for the expected union literal elements and confirm the generated JSON includes the three literals shown.

Written by the indexing model from the issue text.

Assessment

Tech stack
react, typescript
Domain
documentation, tooling
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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