indexedDB setVersion request being blocked?

Question

I'm trying to use indexedDB with jax webGL framework but for some reason setVersion isn't working.

Here's the relevant coffeescript

if @indexedDB and @objectStore and @key
  idb_request = indexedDB.open @indexedDB
  idb_request.onsuccess = (e) =>
    idb = e.target.result

    if idb.objectStoreNames.contains @objectStore
      store = idb.transaction([@objectStore], IDBTransaction.READ_WRITE).objectStore(@objectStore)

    else

      console.log idb.version # => ""

      version_request = idb.setVersion(0.1)
      version_request.onblocked = (e) -> console.log e #=> this one fires
      version_request.onerror = (e) -> console.log e
      version_request.onsuccess = (e) -> console.log e
      version_request.onfailure = (e) -> console.log e

  idb_request.onerror = (e) -> console.log "ERROR: Unable to open indexedDB"

...

The only handler attached to the version request that fires is onblocked, But i'm not even sure what it means for the request to be blocked or why this would happen...

Why would a version request be blocked?

Answer 1

According to the IndexedDB spec it's possible a blocked event might be sent if a database connection is still open while a version change request is made. See: http://www.w3.org/TR/IndexedDB/#version_change-transaction-steps

Here's the text from the spec:

3. If running asynchronously and any of the connections in openDatabases are still not closed, queue up a blocked event for the request.

FWIW: I couldn't reproduce this issue in Jax; I know better than to say it isn't possible, but it's looking unlikely to be a bug in the framework at this time. The corresponding Jax issue is: https://github.com/sinisterchipmunk/jax/issues/37