IDBObjectStore: deleteIndex() method
====================================

 The **`deleteIndex()`** method of the
 `IDBObjectStore` interface destroys the index with the specified name in
 the connected database, used during a version upgrade.

 Note that this method must be called only from a `VersionChange` transaction
 mode callback. Note that this method synchronously modifies the
 `IDBObjectStore.indexNames` property.

**Note:** This feature is available in Web Workers

Syntax
------


```js
deleteIndex(indexName)
```

### Parameters

`indexName`

The name of the existing index to remove.

### Return value

None (`undefined`).

### Exceptions

`InvalidStateError` `DOMException`

Thrown if the method was not called from a `versionchange` transaction mode callback.

`TransactionInactiveError` `DOMException`

Thrown if the transaction this `IDBObjectStore` belongs to is not active (e.g. has been deleted or removed.)

`NotFoundError` `DOMException`

Thrown if there is no index with the given name (case-sensitive) in the database.

Examples
--------

 In the following example you can see
 the `onupgradeneeded` handler being used to update the
 database structure if a database with a higher version number is loaded.
 `IDBObjectStore.createIndex` is used to create new indexes on the object
 store, after which we delete the unneeded old indexes with `deleteIndex()`.
 For a full working example, see our
 To-do Notifications app (view example live).


```js
let db;

// Let us open our database
const DBOpenRequest = window.indexedDB.open("toDoList", 4);

// these two event handlers act on the database being opened successfully, or not
DBOpenRequest.onerror = (event) => {
  note.innerHTML += "<li>Error loading database.</li>";
};

DBOpenRequest.onsuccess = (event) => {
  note.innerHTML += "<li>Database initialized.</li>";

  // store the result of opening the database in the db variable. This is used a lot below
  db = event.target.result;

  // Run the displayData() function to populate the task list with all the to-do list data already in the IDB
  displayData();
};

// This event handles the event whereby a new version of the database needs to be created
// Either one has not been created before, or a new version number has been submitted via the
// window.indexedDB.open line above
//it is only implemented in recent browsers
DBOpenRequest.onupgradeneeded = (event) => {
  const db = event.target.result;

  db.onerror = (event) => {
    note.innerHTML += "<li>Error loading database.</li>";
  };

  // Create an objectStore for this database
  const objectStore = db.createObjectStore("toDoList", {
    keyPath: "taskTitle",
  });

  // define what data items the objectStore will contain

  objectStore.createIndex("hours", "hours", { unique: false });
  objectStore.createIndex("minutes", "minutes", { unique: false });
  objectStore.createIndex("day", "day", { unique: false });
  objectStore.createIndex("month", "month", { unique: false });
  objectStore.createIndex("year", "year", { unique: false });
  objectStore.createIndex("notified", "notified", { unique: false });

  objectStore.deleteIndex("seconds");
  objectStore.deleteIndex("contact");
};
```

Specifications
--------------

| Specification |
| --- |
| Indexed Database API 3.0 # ref-for-dom-idbobjectstore-deleteindex① |

Browser compatibility
---------------------

BCD tables only load in the browser with JavaScript enabled. Enable JavaScript to view data.

See also
--------

* Using IndexedDB
* Starting transactions: `IDBDatabase`
* Using transactions: `IDBTransaction`
* Setting a range of keys: `IDBKeyRange`
* Retrieving and making changes to your data: `IDBObjectStore`
* Using cursors: `IDBCursor`
* Reference example: To-do Notifications (View the example live).