IDBObjectStore: openCursor() method

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨July 2015⁩.

Note: This feature is available inWeb Workers.

TheopenCursor() method of theIDBObjectStore interface returns anIDBRequest object,and, in a separate thread, returns a newIDBCursorWithValue object.Used for iterating through an object store with a cursor.

Syntax

openCursor()openCursor(query)openCursor(query, direction)

Parameters

queryOptional

A key orIDBKeyRange to be queried. If a single valid key is passed,this will default to a range containing only that key. If nothing is passed, this willdefault to a key range that selects all the records in this object store.

directionOptional

A string telling the cursor which direction to travel. The default isnext. Valid values are:

next: The cursor is opened at the start of the store; then, the cursor returns all records, even duplicates,in the increasing order of keys.
nextunique: The cursor is opened at the start of the store; then, the cursor returns all records, that are not duplicates,in the increasing order of keys.
prev: The cursor is opened at the end of the store; then, the cursor returns all records, even duplicates,in the decreasing order of keys.
prevunique: The cursor is opened at the end of the store; then, the cursor returns all records, that are not duplicates,in the decreasing order of keys.

Return value

AnIDBRequest object on which subsequent events related to this operation are fired.

If the operation is successful, the value of the request'sresult property is:

anIDBCursorWithValue object pointing at the first record matching the given query
null if no matching records were found.

Exceptions

This method may raise aDOMException of one of the following types:

InvalidStateErrorDOMException: Thrown if thisIDBObjectStore orIDBIndex has been deleted.
TransactionInactiveErrorDOMException: Thrown if thisIDBObjectStore's transaction is inactive.
DataErrorDOMException: Thrown if the specified key or key range is invalid.

Examples

In this simple fragment we create a transaction, retrieve an object store, then use acursor to iterate through all the records in the object store:

const transaction = db.transaction("name", "readonly");const objectStore = transaction.objectStore("name");const request = objectStore.openCursor();request.onsuccess = (event) => {  const cursor = event.target.result;  if (cursor) {    // cursor.value contains the current record being iterated through    // this is where you'd do something with the result    cursor.continue();  } else {    // no more results  }};