React Passes Unrecognized HTML Attributes Like the Popover API Directly Through to the DOM

They cannot work in React at all, since React only supports a fixed allowlist of HTML attributes defined in its own type system

React passes attributes it does not explicitly recognize straight through to the underlying DOM element unchanged, so the Popover API attributes function correctly at runtime in browsers that support them - TypeScript users may separately need a type assertion until React's official types include these attributes

The Popover API requires a polyfill package to be installed before it can be referenced anywhere inside JSX

React silently strips any attribute not present in its type definitions before rendering, regardless of runtime support