IDBFactory.cmp()
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: 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.
Syntax
var result = window.indexedDB.cmp(a, b);
Returns
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 |
Exceptions
This method may raise a DOMException of the following types:
| Attribute | Description |
|---|---|
DataError |
One of the supplied keys was not a valid key. |
Example
var a = 1; var b = 2; var result = window.indexedDB.cmp(a, b); console.log( "Comparison results: " + result );
Parameters
- first
- The first key to compare.
- second
- The second key to compare.
Specifications
| 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 24 |
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
- 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.)
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/api/idbfactory/cmp