IDBVersionChangeEvent.oldVersion - Web APIs 编辑

The oldVersion read-only property of the IDBVersionChangeEvent interface returns the old version number of the database.

When the opened database doesn't exist yet, the value of oldVersion is 0.

Note:

Syntax

var oldVersion = IDBVersionChangeEvent.oldVersion

Value

A 64-bit integer.

Example

var dbName = "sampleDB";
var dbVersion = 2;
var request = indexedDB.open(dbName, dbVersion);

request.onupgradeneeded = function(e) {
  var db = request.result;
  if (e.oldVersion < 1) {
    db.createObjectStore("store1");
  }

  if (e.oldVersion < 2) {
    db.deleteObjectStore("store1");
    db.createObjectStore("store2");
  }

  // etc. for version < 3, 4...
};

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.)