Are you aware that your if options.maxAge was created by a new String(...) call, this will always return an error? Your timespan method does a typeof x === 'string' but typeof new String('foo') === object.

I didn't think about that case, I reused one function we already have. I'll take a look to it.

I just stumbled over it when looking at the implementation of that function. I guess different rules apply now since it has to deal with external input.

I just took the same approach used in sign() https://github.com/auth0/node-jsonwebtoken/blob/master/sign.js#L114-L116 so that we can cover when the format of the string itself is not correct.

I think it would be nicer for the user to generally test for string with something like
https://github.com/lodash/lodash/blob/master/isString.js, but that might better be done in a different PR.

I wanted to merge a bunch of "breaking changes" and then increase major version. It seems creators of the others PRs forgot about them (we asked for changes).
So, I'll try to find time to fix them probably, but I don't have ETA for now.

why not simply ms(ms(options.maxAge))?

ms(ms(number)) => number
ms(ms(string)) => string
We want end up having the number.

Ok, thanks, got it.

To add to the conversation above, both ms(String('1s')) and ms(String(1000)) work. No need to use new, as String object can be used as a global constructor for strings.

Well, it is the consumer who is deciding what to send. But thanks to your comment I realized I didn't add a test for String('12s'), I'll add it later.

Makes sense - thanks for noting that!

All the other multi-tests have different representations of the same time; this is different. Seems like a mistake?

Yep, copy&paste mistake. Fixing.