IDBKeyRange.lowerBound()

The lowerBound() method of the IDBKeyRange interface creates a new key range with only a lower bound. By default, it includes the lower endpoint value and is closed.

Note: This feature is available in Web Workers

Syntax

var myIDBKeyRange = IDBKeyRange.lowerBound(lower);
var myIDBKeyRange = IDBKeyRange.lowerBound(lower, open);

Parameters

lower 
specifies the lower bound of the new key range. 
open Optional
indicates whether the lower bound excludes the endpoint value. The default is false. 

Return value

IDBKeyRange: The newly created key range.

Exceptions

This method may raise a DOMException of the following type:

Exception Description
DataError

The value parameter passed was not a valid key.

Example

The following example illustrates how you'd use a lower bound key range. Here we declare keyRangeValue = IDBKeyRange.lowerBound("F", false); — a range that includes the value "F" and everthing after it. We open a transaction (using IDBTransaction) and an object store, and open a Cursor with IDBObjectStore.openCursor, declaring keyRangeValue as its optional key range value. This means that the cursor will only retrieve the record with the key value "F" and all that come after it. If we used IDBKeyRange.lowerBound("F", true);, then the range would not include "F"; only the values after it.

Note: For a more complete example allowing you to experiment with key range, have a look at our IDBKeyRange-example repo (view the example live too.)

function displayData() {
  var keyRangeValue = IDBKeyRange.lowerBound("F");

  var transaction = db.transaction(['fThings'], 'readonly');
  var objectStore = transaction.objectStore('fThings');

  objectStore.openCursor(keyRangeValue).onsuccess = function(event) {
    var cursor = event.target.result;
      if(cursor) {
        var listItem = document.createElement('li');
        listItem.innerHTML = '<strong>' + cursor.value.fThing + '</strong>, ' + cursor.value.fRating;
        list.appendChild(listItem);

        cursor.continue();
      } else {
        console.log('Entries all displayed.');
      }
    };
  };

Specifications

Specification
Indexed Database API 3.0 (Indexed DB 3.0)
# ref-for-dom-idbkeyrange-lowerbound①

Browser compatibility

BCD tables only load in the browser

See also