Angular class decorator to track the page visit

page-analytics.ts

/**
 * Angular class decorator to track the page visit
 * 
 */

import { Injector } from '@angular/core';
import { AnalyticService } from '../analytics.service';

export function PageAnalytics(pageName: string) {
  return function (constructor: Function) {
    // Note: AnalyticService is used to illustrate the injection of dependency in decorator responsible for tracking 
    let injector = Injector.create({
      providers: [{ provide: AnalyticService, useClass: AnalyticService }],
    });

    const analyticsService = injector.get(AnalyticService);
    const originalNgOnInit = constructor.prototype.ngOnInit;

    constructor.prototype.ngOnInit = function () {
      analyticsService.track(pageName);
      originalNgOnInit && originalNgOnInit.apply(this);
    };
  };
}


/**
 * How to use it?
 * 
 * @PageAnalytics('customerPage') 
 * export class CustomersComponent implements OnInit {
 * ........
 * }
 * 
 */