IDBFactory: cmp() method

{{ APIRef("IndexedDB") }} {{AvailableInWorkers}}

The cmp() method of the {{domxref("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

cmp(first, second)

Parameters

• first
  • : The first key to compare.
• second
  • : The second key to compare.

Return value

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

Exceptions

• DataError {{domxref("DOMException")}}
  • : Thrown if one of the supplied keys was not a valid key.

Examples

const a = 1;
const b = 2;
const result = window.indexedDB.cmp(a, b);
console.log(`Comparison results: ${result}`);

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• Using IndexedDB
• Starting transactions: {{domxref("IDBDatabase")}}
• Using transactions: {{domxref("IDBTransaction")}}
• Setting a range of keys: {{domxref("IDBKeyRange")}}
• Retrieving and making changes to your data: {{domxref("IDBObjectStore")}}
• Using cursors: {{domxref("IDBCursor")}}
• Reference example: To-do Notifications (View the example live).