您无法直接变更对象存放区索引中的值。您可以变更对象存放区中对象的值，IndexedDB会将您的变更传播到相关索引。索引基本上是只读的。

这是可能的，因为您指定了索引，否则可能需要其他逻辑。
正如你应该知道的，IDBObjectStore有一个方法**.put（）**，它将接收两个参数。使用它你可以放置一个新值或更新一个值。
放置（项，键）项：您要放置/更新的项关键字：可选：您要更新的项目的主要对象存储密钥（如uuid、随机数，简称...）。
编码：

//This is an example only.
    //Let's think that we have an object store into our IndexDB 'user', where object store is called by user-data: 
    //#  Key              Value
    //0   1     { username: 'John Doe' } 

    //Here, we are receiving the 'success' result from an indexedDB.open(), and using its result with a promise.
    dbPromise.then(db => {
            //Getting the transaction
            const transaction = db.transaction('user-data', 'readwrite')
            //Getting the objectStore with the data, the same object store before.
            const store = transaction.objectStore('user-data')
            //Getting the key's object store, in the other other words, this is the key you define when you create you objectStore, with createObjectStore. In this example, I've used 'autoIncrement: true'
            const query = store.get(1)
            
            //Getting the query result with a success listener.
            query.addEventListener('success', event => {
                const { ['result']: user } = event.target
                user.productsIntoCart.push(newItem)
                
                //With this, we will be able to change the object store value.  
                user.username = 'Jane Doe'
                store.put(user, 1)
            })
            query.addEventListener('error', event => console.error(event))
            transaction.addEventListener('complete', () => db.close())
        })
        
    //#  Key              Value
    //0   1     { username: 'Jane Doe' }

您可以在MDN IDBObjectStore.put文档中查看所需的更多详细信息。IDBObjectStore