Verify the use of IDBVersionChangeEventInit On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". event = new IDBVersionChangeEvent('default') PASS event instanceof IDBVersionChangeEvent is true PASS event.type is "default" PASS event.oldVersion is 0 PASS event.newVersion is null PASS event.dataLoss is "none" initEvent = {oldVersion: 123, newVersion: 456} event = new IDBVersionChangeEvent('foo', initEvent) PASS event instanceof IDBVersionChangeEvent is true PASS event.type is "foo" PASS event.oldVersion is initEvent.oldVersion PASS event.newVersion is initEvent.newVersion PASS event.dataLoss is "none" initEvent = {oldVersion: 124, newVersion: 457, dataLoss: 'total'} event = new IDBVersionChangeEvent('foo2', initEvent) PASS event instanceof IDBVersionChangeEvent is true PASS event.type is "foo2" PASS event.oldVersion is initEvent.oldVersion PASS event.newVersion is initEvent.newVersion PASS event.dataLoss is initEvent.dataLoss initEvent = {oldVersion: 'legacy', newVersion: null} event = new IDBVersionChangeEvent('bar', initEvent) PASS event instanceof IDBVersionChangeEvent is true PASS event.type is "bar" PASS event.oldVersion is 0 PASS event.newVersion is null PASS event.dataLoss is "none" PASS successfullyParsed is true TEST COMPLETE