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 everything 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 # ref-for-dom-idbkeyrange-lowerbound① |
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.)