Function get_cb_info 

pub unsafe fn get_cb_info(
    env: Env,
    cbinfo: CallbackInfo,
    argc: *mut usize,
    argv: *mut Value,
    this_arg: *mut Value,
    data: *mut *mut c_void,
) -> Result<(), Status>

Available on crate feature napi-1 only.

napi_get_cb_info