Inconsistent Handling of Attributes in Custom Elements

“Bug: React Handles Native Attributes Incorrectly for Custom Elements, Causing Runtime Errors The common/global HTML attributes are treated differently between native elements and Custom Elements. For example, `<input aria-invalid={true}>` in React produces `<input aria-invalid="true">` in the HTML. But `<custom-element aria-invalid={true}>` in React produces `<custom-element aria-invalid>` in the HTML. This leads to an inconsistent and bug-prone DX. In some cases, it also results in runtime errors. Relates to: #32251 **React Version**: 19.1.1 ## Steps To Reproduce #### For the `form` Attribute 1. Create a form-associated Custom Element 2. Define a `form` _getter_ on it (similar to native form controls) 3. In React, attempt to point the Custom Element's `form` attribute to a specific `<form>` element #### For the `aria-invalid` Attribute 1. Create a Custom Element 2. In React, set the Custom Element's `aria-invalid` attribute to `true` Example Reproduction: https://stackblitz.com/edit/react-custom-elements-global-attrs?file=src%2FApp.tsx,index.html&terminal=dev ## The current behavior #### For the `form` Attribute An error is thrown at runtime, because React tries to set a `getter` instead of altering the form `attribute` (which is what happens for native form controls). #### For the `aria-invalid` Attribute The attribute is set to an empty string (`""`) as if it were a literal [boolean attribute](https://developer.mozilla.org/en-US/docs/Glossary/Boolean/HTML). ## The expected behavior #### For the `form` Attribute An error should not be thrown, and React should not attempt to set a JS Property. Instead, React should treat the attribute the same way it does for native form controls, setting the attribute only. #### For the `aria-invalid` Attribute The attribute should be treated the same way as it is for other native elements: `aria-invalid={true}` should become `aria-invalid="true"` and `aria-invalid={false}` should become `aria-invalid="false"`. The overall expectation beyond these 2 things is that for any attribute in the set of "common/native attributes", React properly updates attributes instead of JS Properties for Custom Elements and native `HTMLElement`s alike, in a consistent manner.”