Google Calendar Integration https://stateful.com/blog/events-in-the-google-calendar-API

Google Calendar Demo.js

const { google } = require("googleapis");

module.exports = async ({ req, res, log }) => {
  const CREDENTIALS = JSON.parse(process.env.CALENDAR_CREDENTIALS);
  const SCOPES = "https://www.googleapis.com/auth/calendar";
  const CALENDAR_ID = process.env.CALENDAR_ID;
  const CALENDAR_TIMEOFFSET = process.env.CALENDAR_TIMEOFFSET;
  const CALENDAR_TIMEZONE = process.env.CALENDAR_TIMEZONE;

  const {
    summary = "This is summary",
    description = "This is the description",
    unixtime = Date.now(),
    calendarId = CALENDAR_ID,
  } = JSON.parse(req.body);

  const calendar = google.calendar({ version: "v3" });

  const auth = new google.auth.JWT(
    CREDENTIALS.client_email,
    null,
    CREDENTIALS.private_key,
    SCOPES
  );

  const dateTimeForCalander = (unixtime) => {
    const date = new Date(unixtime);

    const year = date.getFullYear();
    let month = date.getMonth() + 1;
    if (month < 10) {
      month = `0${month}`;
    }
    let day = date.getDate();
    if (day < 10) {
      day = `0${day}`;
    }
    let hour = date.getHours();
    if (hour < 10) {
      hour = `0${hour}`;
    }
    let minute = date.getMinutes();
    if (minute < 10) {
      minute = `0${minute}`;
    }
    const newDateTime = `${year}-${month}-${day}T${hour}:${minute}:00.000${CALENDAR_TIMEOFFSET}`;
    const event = new Date(Date.parse(newDateTime));
    const startDate = event;

    const endDate = new Date(
      new Date(startDate).setHours(startDate.getHours() + 1)
    );
    return {
      start: startDate,
      end: endDate,
    };
  };

  const insertEvent = async (event) => {
    const response = await calendar.events.insert({
      auth: auth,
      calendarId,
      resource: event,
    });

    if (response["status"] == 200 && response["statusText"] === "OK") {
      return "Event Inserted sucessfully";
    } else {
      return "Failed to insert event";
    }
  };

  const dateTime = dateTimeForCalander(unixtime);

  const event = {
    summary,
    description,
    start: {
      dateTime: dateTime["start"],
      timeZone: CALENDAR_TIMEZONE,
    },
    end: {
      dateTime: dateTime["end"],
      timeZone: CALENDAR_TIMEZONE,
    },
  };

  let result = "";

  try {
    log("Insert event begin");
    result = await insertEvent(event);
    log(`Insert event end RESULT=${result}`);
  } catch (error) {
    error(`Insert event error ERROR=${String(error)}`);
    throw error;
  }

  return res.send(
    JSON.stringify({
      response: result,
      error: false,
    })
  );
};