njs_string_prototype_value_of(njs_vm_t *vm, njs_value_t *args, njs_uint_t nargs,
    njs_index_t unused)
{
    njs_value_t  *value;

    value = &args[0];

    if (value->type != NJS_STRING) {

        if (njs_is_object_string(value)) {
            value = njs_object_value(value);

        } else {
            njs_type_error(vm, "unexpected value type:%s",
                           njs_type_string(value->type));
            return NJS_ERROR;
        }
    }

    vm->retval = *value;

    return NJS_OK;
}