Workaround for IE throwing InvalidAccessError on db open. Fixes #32

[jonohill]

Despite typeof dbVersion equalling "number" in IE, it throws an InvalidAccessError when attempting to call open. parseInt still results in dbVersion being a number, as you'd expect, but seems to remind IE of what it's getting.

[houndci-bot]

Line exceeds maximum allowed length

[jonohill]

I've been doing a bit more research on this one. The real issue actually stems from the behaviour of Math.max in the upgradeDatabase function - if passing a single argument it appears the result is not integery enough - Number.isInteger returns true but indexedDB.open fails. Passing two or more args to Math.max makes everything fine.

I found a bug report at Microsoft Connect which covers the Math.max issue but it 404s to I've made a new one covering it and the interaction with indexedDB.open. I wouldn't hold out too much hope as the old bug report was filed in 2011.

As for what to do here, there are at least a few options, such as:

• Use parseInt with .open, per this pull request.
• Move parseInt to the source of the issue, i.e. dbVersion = parseInt(Math.max.apply(...)
• Skip Math.max if there's only one version

I'm thinking option 3. Thoughts?

As for making this IE specific, I can't think of a nice way to test for the bad behaviour. The result of Math.max looks like an integer in all the tests I have tried, and testing specifically for IE is increasingly messy, especially with MS Edge which tries its hardest to look like Chrome.

[bramski]

Option 3 sounds just fine. Make sure you generate the source files and run the tests before you resubmit a PR.

[jonohill]

Closing this PR. See #38 with the new fix.