nominaltypes06.ts

type HTMLSafeString = string & Nominal<HTMLSafeString>;

  function parseHTMLSafeString(maybeSafeString: string): HTMLSafeString {
  return specialHTMLEscaping(maybeSafeString) as HTMLSafeString;
}
  
function Foo({ userEnteredInput }: { userEnteredInput: HTMLSafeString }) {
  return <div dangerouslySetInnerHTML={{ __html: userEnteredInput }} />;
}
  
function App() {
  return (
    <>
      {/* Type 'string' is not assignable to type 'HTMLSafeString'. */}
      <Foo userEnteredInput="<script>do-something-nasty</script>" />
      {/* OK */}
      <Foo userEnteredInput={parseHTMLSafeString("<script>do-something-nasty</script>")} />
    </>
  );
}