availability-js

A small, client-side library for computing calendar availability. Define weekly working hours, add date-specific overrides, and exclude existing bookings — all with full timezone support. No server required.

Features

• Weekly schedule — Define availability per day of week (e.g. Mon 9–5, Wed 9–5)
• Date overrides — Override specific dates with custom hours or mark days unavailable
• Bookings — Exclude existing bookings when computing available slots
• Timezone-aware — Schedules in one timezone, query in another; bookings in UTC
• Lightweight — Uses date-fns and date-fns-tz; tree-shakeable

Quick example

import {
  getAvailableTimeslots,
  DAY_OF_WEEK,
  type WeeklySchedule,
} from 'availability-js';

const schedule: WeeklySchedule = {
  schedule: [
    { dayOfWeek: DAY_OF_WEEK.Monday, start: '09:00', end: '17:00' },
    { dayOfWeek: DAY_OF_WEEK.Wednesday, start: '09:00', end: '17:00' },
  ],
  timezone: 'Europe/London',
};

const slots = getAvailableTimeslots({
  weeklySchedule: schedule,
  date: new Date('2024-12-09'),
  timezone: 'Europe/London',
  slotDurationMinutes: 30,
});

// → Array of { start, end, isAvailable } slots

Next steps