about.page.ts

import { Component, OnInit, OnDestroy } from "@angular/core";
import { AboutService } from "./about.service";
import { Subscription } from "rxjs";

@Component({
  selector: "app-about",
  templateUrl: "./about.page.html",
  styleUrls: ["./about.page.scss"]
})
export class AboutPage implements OnInit, OnDestroy {
  about: string;
  private aboutSubs: Subscription;

  constructor(private aboutService: AboutService) {}

  ngOnInit() {
    this.aboutSubs = this.aboutService.showAbout().subscribe(data => {
      this.about = data.section[0].text.div;
    });
  }

  ngOnDestroy() {
    if (this.aboutSubs) {
      this.aboutSubs.unsubscribe();
    }
  }
}