[reaxct-dom] Support maskType SVG prop

[everettbu]

Mirror of facebook/react#35921
Original author: sleitor

---

Summary

React currently does not recognize the maskType prop on SVG elements, causing:

1. The attribute to be rendered as-is (maskType="luminance") rather than the correct mask-type="luminance"
2. A React warning: "React does not recognize the maskType prop on a DOM element"

The SVG mask-type attribute is valid per MDN and specifies whether a mask is used as a luminance or alpha mask.

Changes

• getAttributeAlias.js: Add ['maskType', 'mask-type'] to the SVG attribute alias map (alphabetically between markerStart and overlinePosition)
• possibleStandardNames.js: Add masktype: 'maskType' entry so the dev-mode warning correctly suggests the camelCase spelling

Test

// Before: renders as <mask maskType="luminance"> + React warning
// After: renders as <mask mask-type="luminance"> correctly
<svg>
  <mask id="m" maskType="luminance">...</mask>
</svg>

Fixes #35920

[greptile-apps]

Greptile Summary

Adds support for the SVG mask-type attribute by mapping the camelCase maskType prop to the hyphenated mask-type DOM attribute. The alias in getAttributeAlias.js is correct, but possibleStandardNames.js is missing the 'mask-type': 'maskType' entry that every other hyphenated SVG attribute includes — this means React won't provide a helpful dev warning when mask-type is used directly as a prop name.

Confidence Score: 3/5

• Low-risk change but incomplete — missing the hyphenated form entry in possibleStandardNames.js breaks the established pattern.
• The alias mapping is correct and well-placed, but the omission of the 'mask-type': 'maskType' entry in possibleStandardNames.js is inconsistent with how every other hyphenated SVG attribute is handled. This means the dev-mode warning won't work when developers use mask-type directly.
• packages/react-dom-bindings/src/shared/possibleStandardNames.js needs the missing 'mask-type': 'maskType' entry added.

Important Files Changed

Filename	Overview
packages/react-dom-bindings/src/shared/getAttributeAlias.js	Correctly adds maskType → mask-type alias in alphabetical order, consistent with existing patterns.
packages/react-dom-bindings/src/shared/possibleStandardNames.js	Adds masktype: 'maskType' but is missing the corresponding 'mask-type': 'maskType' entry that all other hyphenated SVG attributes include.

_{Last reviewed commit: f54905d}

[greptile-apps]

_{2 files reviewed, 1 comment}

_{Edit Code Review Agent Settings | Greptile}

[greptile-apps]

Missing hyphenated 'mask-type' entry

Every other hyphenated SVG attribute in this file includes both the lowercased form and the hyphenated form (e.g., markerstart / 'marker-start', clippath / 'clip-path', etc.). The 'mask-type': 'maskType' entry is missing here.

Without it, if a developer writes mask-type directly as a prop (the actual SVG attribute name), React won't map it to maskType and won't provide a helpful dev-mode warning suggesting the correct camelCase spelling.

Suggested change

	masktype: 'maskType',
	masktype: 'maskType',
	'mask-type': 'maskType',

Prompt To Fix With AI

This is a comment left during a code review.
Path: packages/react-dom-bindings/src/shared/possibleStandardNames.js
Line: 317

Comment:
**Missing hyphenated `'mask-type'` entry**

Every other hyphenated SVG attribute in this file includes both the lowercased form and the hyphenated form (e.g., `markerstart` / `'marker-start'`, `clippath` / `'clip-path'`, etc.). The `'mask-type': 'maskType'` entry is missing here.

Without it, if a developer writes `mask-type` directly as a prop (the actual SVG attribute name), React won't map it to `maskType` and won't provide a helpful dev-mode warning suggesting the correct camelCase spelling.

```suggestion
  masktype: 'maskType',
  'mask-type': 'maskType',
```

How can I resolve this? If you propose a fix, please make it concise.

[everettbu]

Upstream PR was closed or merged. Code is synced via branch mirror.