Outlook Calendar API integration with website

Integrating Outlook Calendar API with Website

Outlook Calendar is part of Microsoft 365. The API is implemented through Microsoft Graph. Used in enterprise tools: appointment scheduling, meeting synchronization, employee availability display.

Microsoft Graph: Reading Events

import { Client } from '@microsoft/microsoft-graph-client';

const client = Client.initWithMiddleware({ authProvider: tokenCredentialAuthProvider });

async function getCalendarEvents(userId: string): Promise<Event[]> {
  const response = await client
    .api(`/users/${userId}/calendarView`)
    .query({
      startDateTime: new Date().toISOString(),
      endDateTime:   new Date(Date.now() + 7 * 86400000).toISOString(),
    })
    .select('subject,start,end,location,isAllDay')
    .orderby('start/dateTime')
    .get();

  return response.value.map((e: any) => ({
    id:       e.id,
    title:    e.subject,
    start:    e.start.dateTime,
    end:      e.end.dateTime,
    location: e.location?.displayName,
    allDay:   e.isAllDay,
  }));
}

Creating Event

async function createEvent(userId: string, booking: Booking): Promise<string> {
  const event = await client.api(`/users/${userId}/events`).post({
    subject:  booking.serviceName,
    start:    { dateTime: booking.startsAt, timeZone: 'Russian Standard Time' },
    end:      { dateTime: booking.endsAt,   timeZone: 'Russian Standard Time' },
    body: {
      contentType: 'HTML',
      content:     `<p>Client: ${booking.customerName}</p><p>Phone: ${booking.phone}</p>`,
    },
    attendees: [{ emailAddress: { address: booking.customerEmail }, type: 'required' }],
    isReminderOn:       true,
    reminderMinutesBeforeStart: 60,
  });
  return event.id;
}

Checking Available Time (FindMeetingTimes)

async function findAvailableSlots(userEmail: string, duration: number) {
  return client.api('/me/findMeetingTimes').post({
    attendees: [{ emailAddress: { address: userEmail }, type: 'required' }],
    timeConstraint: {
      timeslots: [{
        start: { dateTime: new Date().toISOString(), timeZone: 'Russian Standard Time' },
        end:   { dateTime: new Date(Date.now() + 7 * 86400000).toISOString(), timeZone: 'Russian Standard Time' },
      }],
    },
    meetingDuration: `PT${duration}M`,
  });
}

Timeline

Reading events + creation via Graph API: 3–4 business days.