Scheduler Remote Data

Instead of passing events up front, hand the scheduler a dataSource: getEvents(start, end) runs whenever the visible range changes, and persistEvents runs after every committed change.

new coreui.Scheduler(element, {
  dataSource: {
    getEvents: async (start, end) =>
      (await fetch(`/api/events?from=${start}&to=${end}`)).json(),

    persistEvents: async ({ action, event, occurrence, scope }) => {
      const response = await fetch('/api/events', {
        method: 'POST',
        body: JSON.stringify({ action, event, occurrence, scope }),
      })
      return { success: response.ok } // success: false reverts the change
    },
  },
})

Behavior

• getEvents receives the visible window as ISO strings (end exclusive) and fires on init and whenever navigation, view switches or update() change the range — never twice for the same range. A spinner (data-part="loading") shows while a request is in flight, and stale responses from superseded requests are discarded.
• A failed load keeps the current events and announces the localizable loadFailed message.
• persistEvents gets the same payload as the eventChange DOM event (minus revert). Returning { success: false } — or throwing — reverts the change and announces saveFailed. The eventChange event still fires first, so analytics and optimistic UI keep working.
• getVisibleRange() returns the current window ({ start, end }) if you prefer wiring fetches yourself through dateChange/viewChange.

Manual wiring

Everything above is also possible without dataSource — listen to dateChange, fetch, call setEvents(), and call revert() from your eventChange listener when the server rejects a change. dataSource is the packaged version of exactly that pattern.