How to make the searchbar search in ionic cards?

Ionic Framework ionic-v3
1

This is what I have and tried to do. I get an error; Runtime Error
Error in ./Page1 class Page1 - caused by: item.toLowerCase is not a function
This is a searchbar with the code from ionic itself. https://ionicframework.com/docs/components/#searchbar
I do not know what to do now, all the help is appreciated!

Thanks in advance!!

`import { Component } from '@angular/core';

import { NavController } from 'ionic-angular';

@Component({
  selector: 'page-page1',
  templateUrl: 'page1.html'
})

export class Page1 {

searchQuery: string = '';
items: any;

getItems(ev: any) {
   this.initializeItems();

   // set val to the value of the searchbar
   let val = ev.target.value;

   if (val && val.trim() != '') {
     this.items = this.items.filter((item) => {
       return (item.toLowerCase().indexOf(val.toLowerCase()) > -1);
     })
   }
 }

  constructor(public navCtrl: NavController) {
this.initializeItems();
   }

   initializeItems(){
   this.items = [
   {name: 'Hasan Sezen', avatar: 'http://placehold.it/100', groep: 'Groep 1'},
   {name: 'Amcik Sezen', avatar: 'http://placehold.it/100', groep: 'Groep 1'},
   {name: 'Pezo Sezen', avatar: 'http://placehold.it/100', groep: 'Groep 1'},
   {name: 'Ala Sezen', avatar: 'http://placehold.it/100', groep: 'Groep 2'},
   {name: 'Ebenin Sezen', avatar: 'http://placehold.it/100', groep: 'Groep 2'},
   {name: 'Ami Sezen', avatar: 'http://placehold.it/100', groep: 'Groep 2'},
   {name: 'Emrah Sezen', avatar: 'http://placehold.it/100', groep: 'Groep 3'},
   {name: 'Danny Sezen', avatar: 'http://placehold.it/100', groep: 'Groep 3'},
   {name: '6pack Sezen', avatar: 'http://placehold.it/100', groep: 'Groep 3'},
   {name: 'Marco van Sezen', avatar: 'http://placehold.it/100', groep: 'Groep 4'},
   {name: 'Shabalasdbah  Sezen', avatar: 'http://placehold.it/100', groep: 'Groep 4'},
   {name: 'Lange namen Sezen', avatar: 'http://placehold.it/100', groep: 'Groep 4 '},
   {name: 'Yarrag Sezen', avatar: 'http://placehold.it/100', groep: 'Groep 3'}
   ];
   }
}
`