JavaScript

newt/ui is written in TypeScript, but the CLI can write plain JavaScript into a project that does not use it.

The registry is TypeScript. If your project is not, set typescript to false in components.json — newtui init asks, and answering no sets it for you — and every file the CLI writes afterwards is JavaScript.

{
  "typescript": false,
  "aliases": {
    "components": "@/components",
    "ui": "@/components/ui",
    "utils": "@/lib/utils"
  }
}

What the CLI strips

The transform is textual and deliberately small, because the components are written so that it can be. It removes:

type annotations on parameters, variables and return values;
interface and type declarations;
import type statements and the type-only specifiers inside a mixed import;
satisfies and as expressions;
generic parameter lists on functions and components.

Runtime code is untouched. The cva variant definitions, the cn calls and the class strings are the same in both languages — the types they carried were inferred from the same objects.

The extension follows tsx: with typescript: false the CLI writes components/ui/button.jsx.

The single file components keep the .vue extension and lose lang="ts" from their <script setup> block. The index.ts barrel becomes index.js.

What you give up

VariantProps is how a React or Vue component states which variants exist. In JavaScript that contract is gone: passing variant="brand" to a button that has no such variant is a silent no-op rather than a type error.

The component pages on this site list every variant for exactly that reason — they are the reference a JavaScript project reads instead of the types.