Send alert if item has already been selected

[Maureen Moore]

public onSubmit(id, product_name){


var data = {
   id,
   product_name
};


this.items.push(data);
localStorage.setItem(this.storageKey, JSON.stringify(this.items));
var retrieverObject = localStorage.getItem('this.items.id');
var retrieveObject = JSON.parse(retrieverObject);
if (retrieveObject == id) {
    alert('test');
}
}

I want to check if the value has already been submitted. This is part of a shopping cart application in which the product quantity will be updated if the product has already been chosen.

When I use

var retrieverObject = localStorage.getItem('MyDataStorageKey');

it returns:

[{"id":0,"product_name":"Adult Male Bike"},{"id":0,"product_name":"Adult Male Bike"}]

All of the following return null

   

var retrieverObject = localStorage.getItem('MyDataStorageKey.findIndex(id)');
var retrieverObject = localStorage.getItem('MyDataStorageKey.indexOf("id")');
var retrieverObject = localStorage.getItem('MyDataStorageKey.indexOf(id)');
var retrieverObject = localStorage.getItem('MyDataStorageKey[0].id');
var retrieverObject = localStorage.getItem('MyDataStorageKey[0]');
var retrieverObject = localStorage.getItem('MyDataStorageKey.findIndex("id")');
var retrieverObject = localStorage.getItem('MyDataStorageKey["id"]');
var retrieverObject = localStorage.getItem('MyDataStorageKey.id');

[Maureen Moore]

All of these return null:

var retrieverObject = localStorage.getItem('items["id"]');

  var retrieverObject = localStorage.getItem('items[0].id');

  var retrieverObject =  localStorage.getItem('items[{"id"}]');

[Maureen Moore]

This is the solution:

var retrieverObject = localStorage.getItem('items');
var retrieveObject = JSON.parse(retrieverObject);
 
if(retrieveObject === null) {
  console.log('no tasks')
} else {
  retrieveObject.forEach(function(el){
   alert("This is the storage id " + el.id);
   if (el.id == id){
   alert(el.id + " same ");
   }
  });
}