how to call a function from other 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 { DataService } from './../services/data.service';
import { Injectable } from '@angular/core';
import { Resolve, ActivatedRouteSnapshot } from '@angular/router';
 
@Injectable({
  providedIn: 'root'
})
export class DataResolverService implements Resolve<any> {
 
  constructor(private dataService: DataService) { }
 
  resolve(route: ActivatedRouteSnapshot) {
    let id = route.paramMap.get('id');
    return this.dataService.getData(id);
  }
}