add module providers

projects/ngx-pwa-install/src/lib/ngx-pwa-install.providers.ts

@@ -0,0 +1,17 @@
+import { InjectionToken } from '@angular/core';
+import { fromEvent, ReplaySubject } from 'rxjs';
+import { tap } from 'rxjs/operators';
+
+export const beforeInstallPromptFactory = () => {
+  const event$ = fromEvent<Event>(window, 'beforeinstallprompt')
+    .pipe(
+      tap(e => e.preventDefault()),
+    );
+  const beforeInstallPromptSubject = new ReplaySubject<Event>();
+  event$.subscribe(beforeInstallPromptSubject);
+  return beforeInstallPromptSubject;
+};
+export const BeforeInstallPrompt = new InjectionToken<ReplaySubject<Event>>('BeforeInstallPrompt', {
+  providedIn: 'root',
+  factory: beforeInstallPromptFactory
+});