app_requires.js

var googleapis = require('googleapis')
, OAuth2Client = googleapis.OAuth2Client
, config = require('./config.json');

var oauth2Client = new OAuth2Client(config.CLIENT_ID, config.CLIENT_SECRET, config.REDIRECT_URL);

config.json

{
    "CLIENT_ID" : "YOUR CLIENT ID",
    "CLIENT_SECRET" : "YOUR CLIENT SECRET",
    "REDIRECT_URL" : "http://example.com/oauth2callback"
}

generic_callbacks.js

var success = function(data) { console.log('success',data); }
var failure = function(data) { console.log('failure',data); }

gotToken.js

var gotToken = function () {
    googleapis
    .discover('mirror', 'v1')
    .execute(function(err, client) {
        if (!!err){
            failure();
            return;
        }
        listTimeline(client, failure, success);
        insertHello(client, failure, success);
    });
};

grabToken.js

var grabToken = function (code, errorCallback, successCallback){
    oauth2Client.getToken(code, function(err, tokens){
        if (!!err){
            errorCallback(err);
        } else {
            console.log('tokens',tokens);
            oauth2Client.credentials = tokens;
            successCallback();
        }
    });
};

insertHello.js

var insertHello = function(client, errorCallback, successCallback){
    client
    .mirror.timeline.insert({"text": "Hello world"})
    .withAuthClient(oauth2Client)
    .execute(function(err, data){
        if (!!err)
            errorCallback(err);
        else
            successCallback(data);
    });
};

listTimeline.js

var listTimeline = function(client, errorCallback, successCallback){
    client
    .mirror.timeline.list()
    .withAuthClient(oauth2Client)
    .execute(function(err, data){
        if (!!err)
            errorCallback(err);
        else
            successCallback(data);
    });
};

routes.js

app.get('/', function(req,res){
    if (!oauth2Client.credentials){
        var url = oauth2Client.generateAuthUrl({
            access_type: 'offline',
            scope: 'https://www.googleapis.com/auth/glass.timeline'
        });
        res.redirect(url);
    } else {
        gotToken();
    }
    res.send('something happened');
    res.end();

});
app.get('/oauth2callback', function(req, res){
    grabToken(req.query.code, failure, function(){ res.redirect('/'); });
});