Mojo JavaScript surface

Select surfaces: ["js"] to use the target’s JavaScript source declarations and the @tsonic/mojo-js runtime. Native Mojo is the default profile.

export function joined(values: string[]): string {
  return values.join(", ");
}

The selected array operation supplies the required runtime contract. This is not JavaScript evaluation inside a VM.

Native strings remain the normal carrier. Explicit JsString values have a separate UTF-16 contract; a surface selection is not a blanket conversion of native strings into UTF-16 objects. Array joining/default sorting preserve their selected source coercions and ordering. Literal and dynamic regular expressions use the JavaScript runtime’s RegExp implementation.

The support inventory identifies executable proof families. It is not a claim that every ECMAScript API or locale behavior exists.