[Angular] Custom a DatePipe to support special time zone conversion from user

Background

It didn't use a time zone format of datetime in database, data has only one time zone.

a. Columns:

b. Data:

So I'll define a custom DatePipe to extend DatePipe in my source code of Angular.

How to implement?

1. Create a pipe class of Angular called MyDatePipe.

Output format: { yyyy/MM/dd HH:mm:ss }

import { DatePipe } from '@angular/common';
import { Pipe, PipeTransform } from '@angular/core';
@Pipe({
  name: 'myDate',
  standalone: true
})
export class MyDatePipe extends DatePipe implements PipeTransform {
  override transform(value: any, args?: any): any {
    let myDate = new Date(value);
    myDate.setHours(myDate.getHours() + args);
    return super.transform(myDate, 'yyyy/MM/dd HH:mm:ss');
  }
}

2. Using it in your component

a. Component

providers: MyDatePipe,

imports: MyDatePipe

import { Component, OnInit, ChangeDetectionStrategy } from '@angular/core';
import { FormsModule } from '@angular/forms';

import { TokenKey, TokenPre } from '@app/config/constant';
import { WindowService } from '@app/core/services/common/window.service';
import { NzButtonModule } from 'ng-zorro-antd/button';
import { NzInputModule } from 'ng-zorro-antd/input';

import { MyDatePipe } from '../../pipes/my-datepipe';

@Component({
  selector: 'app-pages-empty',
  templateUrl: './empty.component.html',
  changeDetection: ChangeDetectionStrategy.OnPush,
  standalone: true,
  providers: [MyDatePipe],
  imports: [NzButtonModule, NzInputModule, FormsModule, MyDatePipe]
})
export class EmptyComponent implements OnInit {
  token?: string;
  srvDate: Date = new Date();
  srvOffsetOfTimeZone: number = 8; // offset of server time zone
  userOffsetOfTimeZone: number = -5.5; // offset of user time zone

  constructor(private windowServe: WindowService, private myDatePipe: MyDatePipe) {}

  ngOnInit(): void {}

  setToken(): void {
    this.windowServe.setSessionStorage(TokenKey, TokenPre + this.token);
  }

  getDate(): void {
    this.srvDate = new Date();
    const userDate = this.myDatePipe.transform(this.srvDate, -this.srvOffsetOfTimeZone + this.userOffsetOfTimeZone);
    console.log(`User date: ${userDate}`);
  }
}

b. Html

<button nz-button (click)="getDate()">Show user date</button>
Server time(UTC {{ srvOffsetOfTimeZone }})：{{ srvDate }}
<br />

UTC time(UTC)： {{ srvDate | myDate : -srvOffsetOfTimeZone }}
<br />
User time(UTC {{ userOffsetOfTimeZone }})：{{ srvDate | myDate : -srvOffsetOfTimeZone + userOffsetOfTimeZone }}

3. Test result