Limiting the range of values in a cursor

How to specify the range and direction of cursors with IndexedDB?

It is possible to use a special object called IDBKeyRange, for "IndexedDB Key Range", and pass it as the first argument to openCursor() or openKeyCursor(). We can specify the bounds of the data we are looking for, by using methods such as upperBound() or lowerBound(). The bound may be "closed" (i.e., the key range includes the given value(s)) or "open" (i.e., the key range does not include the given value(s)). 

Let's look at some examples (adapted from this MDN article):

// Only match "Donna"

var singleKeyRange = IDBKeyRange.only("Donna");

// Match anything past "Bill", including "Bill"

var lowerBoundKeyRange = IDBKeyRange.lowerBound("Bill");

// Match anything past "Bill", but don't include "Bill"

var lowerBoundOpenKeyRange = IDBKeyRange.lowerBound("Bill", true);

// Match anything up to, but not including, "Donna"

var upperBoundOpenKeyRange = IDBKeyRange.upperBound("Donna", true);

// Match anything between "Bill" and "Donna", but not including "Donna"

var boundKeyRange = IDBKeyRange.bound("Bill", "Donna", false, true);

// To use one of the key ranges, pass it in as the first argument of openCursor()/openKeyCursor()

index.openCursor(boundKeyRange).onsuccess = function(event) {

    var cursor = event.target.result;

    if (cursor) {

        // Do something with the matches.

        cursor.continue();

    }

};

Complete example

Adapted from an example on gitHub, today no more available (original URL):

Try the online example at JsBin (enter "Gaming", "Batman" etc. as key range values):