Web/API/IDBCursor/key

The key read-only property of the IDBCursor interface returns the key for the record at the cursor's position. If the cursor is outside its range, this is set to undefined. The cursor's key can be any data type.

Note: This feature is available in Web Workers.

Syntax

var key = cursor.key;

Value

A value of any type.

Example

In this simple fragment we create a transaction, retrieve an object store, then use a cursor to iterate through all the records in the object store. Within each iteration we log the key of the cursor to the console, something like this (its the album title in each case, which is our key).

The cursor does not require us to select the data based on a key; we can just grab all of it. Also note that in each iteration of the loop, you can grab data from the current record under the cursor object using cursor.value.foo. For a complete working example, see our IDBCursor example ([[../../../../../../../mdn.github.io/indexeddb-examples/idbcursor/index|view example live]].)

function displayData() {
  var transaction = db.transaction(['rushAlbumList'], "readonly");
  var objectStore = transaction.objectStore('rushAlbumList');

  objectStore.openCursor().onsuccess = function(event) {
    var cursor = event.target.result;
    if(cursor) {
      var listItem = document.createElement('li');
      listItem.innerHTML = cursor.value.albumTitle + ', ' + cursor.value.year;
      list.appendChild(listItem);  
      
      console.log(cursor.key);
      cursor.continue();
    } else {
      console.log('Entries all displayed.');
    }
  };
};

Specifications

Specification	Status	Comment
Indexed Database API 2.0The definition of 'key' in that specification.	Recommendation
Indexed Database API DraftThe definition of 'key' in that specification.	Recommendation

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`key`	Chrome Full support 24 Full support 24 No support 23 — 24 Prefixed' Prefixed' Implemented with the vendor prefix: webkit	Edge Full support 12	Firefox Full support 16 Full support 16 No support 10 — 16 Prefixed' Prefixed' Implemented with the vendor prefix: moz	IE Partial support 10	Opera Full support 15	Safari Full support 7	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android Full support 22	Opera Android Full support 14	Safari iOS Full support 8	Samsung Internet Android Full support Yes
Binary keys	Chrome Full support 58	Edge Full support ≤79	Firefox Full support 51	IE ?	Opera Full support 45	Safari Full support 10.1	WebView Android Full support 58	Chrome Android Full support 58	Firefox Android ?	Opera Android Full support 43	Safari iOS Full support 10.3	Samsung Internet Android Full support 7.0

Legend

Full support: Full support
Partial support: Partial support
Compatibility unknown: Compatibility unknown
Requires a vendor prefix or different name for use.': Requires a vendor prefix or different name for use.