IDBFactory.cmp() - Web APIs 编辑

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:

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 = indexedDB.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

This method may raise a DOMException of the following types:

Example

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

Specifications

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.)