How to add new event to google calendar by node

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Node.js

Hi,

I am very new to node. I am using expressjs.
Here my requirement is to insert an event to google calendar. After googling if found following block of code:

var moment = require('moment');
var googleapis = require('googleapis');
var GoogleToken = require('gapitoken');
var OAuth2Client = googleapis.OAuth2Client;

var token = new GoogleToken({
    iss: '*******************@developer.gserviceaccount.com',
    scope: 'https://www.googleapis.com/auth/calendar',
    keyFile: './*****************.pem'
}, function (err) {
    if (err) {
        return console.log(err);
    }

    token.getToken(function (err, token) {
        if (err) {
            return console.log(err);
        }

        googleapis.load('calendar', 'v3', function (err, client) {
            var oauthClient = new OAuth2Client('', '', '', {}, {
                token_type: 'Bearer',
                access_token: token
            });

            var now = moment().format();

            client
                .calendar
                .events
                .insert({
                    calendarId: 'primary',
                    resource: {
                        summary: 'hangout',
                        description: 'hangout',
                        reminders: {
                            overrides: {
                                method: 'popup',
                                minutes: 0
                            }
                        },
                        start: {
                            dateTime: now
                        },
                        end: {
                            dateTime: now
                        },
                        attendees: [{
                            email: '****@**********.com'
                        }]
                    }
                })
                .withAuthClient(oauthClient)
                .execute(function (err, event) {
                    // event does not contain hangoutLink
                    console.log(event.hangoutLink);
                });
        });
    });
});

But here I dont understand the 'iss', 'scope' and 'keyfile'.

Please help me in this or let me know if any other easy way are there.

My basic requirement to add an event to the calendar.

Thanks
Swarup