TypeScript: Best way to create Data access layer

If you want to build this behavior, you can simply implement the Strategy pattern

Example:

import { Injectable } from "@angular/core";import { fromEvent, merge } from "rxjs";import { startWith, map } from "rxjs/operators";interface Strategy {  getData1(): any;  anotherMethod(): any;}class SQLStrategy implements Strategy {  getData1() {    console.log("SQl", "getData1");  }  anotherMethod() {    console.log("SQl", "anotherMethod");  }}class HTTPStrategy implements Strategy {  getData1() {    console.log("HTTP", "getData1");  }  anotherMethod() {    console.log("HTTP", "anotherMethod");  }}@Injectable()export class DataLayerService {  private strategy;  constructor() {    // init strats    const sqlStrategy = new SQLStrategy();    const httpStrategy = new HTTPStrategy();    merge(fromEvent(window, "online"), fromEvent(window, "offline"))      .pipe(        startWith(1),        map(x => navigator.onLine)      )      .subscribe(x => {        console.log("navigator.onLine", x);        this.strategy = x ? httpStrategy : sqlStrategy;      });  }  public getData1() {    this.strategy.getData1();  }  public anotherMethod() {    this.strategy.anotherMethod();  }}

Stackblitz:https://stackblitz.com/edit/angular-ivy-fggs4r?file=src/app/data-layer.service.ts