how to call a function from another page in ionic code example

Example 1: passing data from one page to another in ionic 4

import { Component, OnInit } from '@angular/core';
import { ActivatedRoute, Router } from '@angular/router';
 
@Component({
  selector: 'app-details',
  templateUrl: './details.page.html',
  styleUrls: ['./details.page.scss'],
})
export class DetailsPage implements OnInit {
 
  data: any;
 
  constructor(private route: ActivatedRoute, private router: Router) {
    this.route.queryParams.subscribe(params => {
      if (this.router.getCurrentNavigation().extras.state) {
        this.data = this.router.getCurrentNavigation().extras.state.user;
      }
    });
  }
 
  ngOnInit() { }
}

Example 2: passing data from one page to another in ionic 4

import { DataResolverService } from './resolver/data-resolver.service';
import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
 
const routes: Routes = [
  { path: '', redirectTo: 'home', pathMatch: 'full' },
  { path: 'home', loadChildren: './home/home.module#HomePageModule' },
  { path: 'details', loadChildren: './details/details.module#DetailsPageModule' },
  {
    path: 'details/:id',
    resolve: {
      special: DataResolverService
    },
    loadChildren: './details/details.module#DetailsPageModule'
  }
];
 
@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }