How to show an message if product is not found after search

Ionic Framework ionic-v3
1

How to show an message if product is not found after searh
below my code

getItems(ev) {
  // Reset items back to all of the items
  this.initializeItems();
console.log(ev);
  // set val to the value of the ev target
  var val = ev.target.value;
  console.log(val)
  // if the value is an empty string don't filter the items
  if (val && val.trim() != '') {
    this.serarchProduct = this.serarchProduct.filter((item) => {
      return (item.product_name.toLowerCase().indexOf(val.toLowerCase()) > -1);
    })
  }
}

Please help me out
any help would be highly appreciated
Thanks