IDBCursor.key - Web APIs 编辑

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:

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 (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

Browser compatibility

BCD tables only load in the browser

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 example live.)