napi_status napi_get_value_external(napi_env env,napi_value value,void** result)
[in] env: The environment that the API is invoked under.[in] value:napi_valuerepresenting JavaScript external value.[out] result: Pointer to the data wrapped by the JavaScript external value.
Returns napi_ok if the API succeeded. If a non-external napi_value is
passed in it returns napi_invalid_arg.
This API retrieves the external data pointer that was previously passed to
napi_create_external().
