The cmp() method of the IDBFactory interface compares two values as keys to determine equality and ordering for IndexedDB operations, such as storing and iterating.

Note: This feature is available in Web Workers.

Note: Do not use this method for comparing arbitrary JavaScript values, because many JavaScript values are either not valid IndexedDB keys (booleans and objects, for example) or are treated as equivalent IndexedDB keys (for example, since IndexedDB ignores arrays with non-numeric properties and treats them as empty arrays, so any non-numeric arrays are treated as equivalent). This throws an exception if either of the values is not a valid key.


var result = window.indexedDB.cmp(a, b);


An integer that indicates the result of the comparison; the table below lists the possible values and their meanings:

Returned value Description
-1 1st key is less than the 2nd key
0 1st key is equal to the 2nd key
1 1st key is greater than the 2nd key


This method may raise a DOMException of the following types:

Attribute Description
DataError One of the supplied keys was not a valid key.


var a = 1;
var b = 2;
var result = window.indexedDB.cmp(a, b);
console.log( "Comparison results: " + result );


The first key to compare.
The second key to compare.


Specification Status Comment
Indexed Database API
The definition of 'cmp' in that specification.
Editor's Draft  

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 23webkit
10 moz
16.0 (16.0)
10, partial 15 7.1
Available in workers (Yes) 37.0 (37.0) ? (Yes) ?
Feature Android Firefox Mobile (Gecko) Firefox OS IE Phone Opera Mobile Safari Mobile
Basic support 4.4 22.0 (22.0) 1.0.1 10 22 8
Available in workers (Yes) 37.0 (37.0) (Yes) ? (Yes) ?

See also


© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.

API cmp Database IDBFactory IndexedDB Method Reference Storage storage