Send alert if item has already been selected

Question

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 · Answer

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 " ); } }); }

Maureen Moore · Answer

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 · Answer

This is an angular app not using jQuery. I can't use the jQuery filter. Thanks anyways Nisha.

Nisha Regil · Answer

You can use jquery filter like this var filterarray = retrieveObject.filter(function (data) { return data.id === id ; }); if data with id already exists filterarray will return length > 0. Also I have a doubt in the var retrieverObject statement you wrote. At one place you are assinging it to localStorage.getItem('this.items.id'); and in another to localStorage.getItem('MyDataStorageKey');