Function native_from_object 

pub(crate) unsafe fn native_from_object<T>(
    cx: &mut JSContext,
    obj: *mut JSObject,
) -> Result<*const T, ()>
where
    T: DomObject + IDLInterface,

Get a *const T for a DOM object accessible from a JSObject.

Safety

obj must point to a valid, non-null JS object. cx must point to a valid, non-null JS context.