Cannot read property 'storageKey' of undefined

Maureen Moore

I have a shopping cart and I only want the products to be set if they don't already exist in localStorage. If the product is already in localStorage, then no new product should be added. Later I will update the quantity if the product already exists in localStorage but I haven't reached that step yet. When I try to set the item when the id isn't in localStorage, I get the TypeError: Cannot read property 'storageKey' of undefined

storageKey = 'MyDataStorageKey';
public onSubmit(id, quantity, product_name){
var data = {
id,
quantity,
product_name,
};
var retrieverObject = localStorage.getItem('items');
var retrieveObject = JSON.parse(retrieverObject);
this.items.push(data);
retrieveObject.forEach(function(el){
alert("This is the storage id " + el.id);
if (el.id == id){
alert(el.id + " same product");
} else {
alert("this id is not in storage ");
//error returns for the following line of code
localStorage.setItem(this.storageKey, JSON.stringify(this.items));
}
});
}

3 Replies

Know the answer? Post it — somebody with the same question will find it here.

Guest User6y ago
In line number 10 u are trying to fetch item from localstorage. Localstorage is initially not set.. so this assignment will give u nothing means undefined. So while setting item.. you must check by if whether the line number 10 returns undefined, null or any item.
+1
Maureen Moore6y ago
The product still gets set after all even when localStorage is set. It's not working as intended but the error message is suppressed.
+1
Maureen Moore6y ago
I got the answer at another forum. Using the arrow function and putting this.items.push(data); in to the else condition fixed the problem!
+1