Saving token.refresh_token to a file

[Marcuzzz]

    myApiOauth.setTokens({
      refresh_token: credentials.refresh_token
    });
  } else {
    myApiOauth.openAuthWindowAndGetTokens()
      .then(token => {
}

I still don't 100% understand what is happening here...
I'm used to using python and a library that creates a file: credentials.storage (json structure/file)

I've tried to recreate this with the google-oauth2
Can google-oauth2 also create a token_response:

    "token_response": {
        "access_token": "",
        "expires_in": 3599,
        "refresh_token": "",
        "scope": "",
        "token_type": "Bearer"
    },

And scope is not a list?

"scope": "https://www.googleapis.com/auth/spreadsheets openid https://www.googleapis.com/auth/userinfo.profile https://www.googleapis.com/auth/drive https://www.googleapis.com/auth/userinfo.email",

I also saw 'openid' what's that?