DevExtreme Angular - Time Zone Support

Appointments are displayed in the client time zone. The time-zone offset specified in the startDate or endDate is also taken into account (if there is any). You can force a time zone for an individual appointment via its startDateTimeZone and endDateTimeZone fields or for all appointments in the widget via its timeZone option. timeZone takes precedence over start/endDateTimeZone.

You can use the following formula to calculate an appointment's resulting time-zone offset:

  • `resultingOffset` = `timeZoneOffset` - `clientOffset` (or `embeddedOffset` if there is any)

where

  • timeZoneOffset is the offset of the timeZone or start/endDateTimeZone.
  • clientOffset is the offset of the client side.
  • embeddedOffset is the offset specified in the start/endDate.

The calculated offset is then added to the date-time value.

For example, if the timeZone is "Europe/Berlin" (UTC offset +1), and the client is in Tokyo (UTC offset +9), the calculated offset is 1 - 9 = -8. The time of all appointments is shifted back 8 hours: the appointment that started at 2019-01-01T12:00:00 starts at 2019-01-01T04:00:00. The same applies when the time-zone offset is specified in the date-time value (2019-01-01T12:00:00+09:00), except that this offset is used instead of the client offset.

Add the following code to allow users to change an appointment's time zone:

app.component.html
app.component.ts
app.module.ts
  • <dx-scheduler ...
  • (onAppointmentFormOpening)="showTimeZoneFields($event)">
  • </dx-scheduler>
  • import { Component } from '@angular/core';
  •  
  • @Component({
  • selector: 'app-root',
  • templateUrl: './app.component.html',
  • styleUrls: ['./app.component.css']
  • })
  • export class AppComponent {
  • showTimeZoneFields(e) {
  • e.form.itemOption("startDateTimeZone", { visible: true });
  • e.form.itemOption("endDateTimeZone", { visible: true });
  • }
  • }
  • import { BrowserModule } from '@angular/platform-browser';
  • import { NgModule } from '@angular/core';
  • import { AppComponent } from './app.component';
  •  
  • import { DxSchedulerModule } from 'devextreme-angular';
  •  
  • @NgModule({
  • declarations: [
  • AppComponent
  • ],
  • imports: [
  • BrowserModule,
  • DxSchedulerModule
  • ],
  • providers: [],
  • bootstrap: [AppComponent]
  • })
  • export class AppModule { }

To allow a user to change the widget's time zone, implement a select box as shown in the Time Zone Support demo.