js-cookie: Support max-age attribute instead of expires

I was about to send a PR for this, but it turns out that even recent versions of Internet Explorer do not support max-age as part of the document.cookie api. I probably misunderstood/misinterpreted the MDN compatibility table here, which is all about the Set-Cookie header. So IE starting with version 9 does understand a cookie header with Max-Age, but that’s it.

Here’s another extensive cookie compatibility reference table with proof: https://inikulin.github.io/cookie-compat/

A developer in need of max-age can always do: Cookies.set('foo', 'bar', { 'max-age': '3600'})

Closing 🤕

Hmmm, max-age is seductively simpler, both in implementation as well as usage. Since the value is the amount of seconds until the cookie expires, we wouldn’t even need to support both a number and a date. Just give us the cookie’s expected age in seconds as a number, that’s it. We wouldn’t even have to have any extra code handling this attribute any longer. We should replace expires with this, for all its simplicity, in v3.

“max-age” integrates with OAuth’s “expires_in” nicely too.

RE: https://tools.ietf.org/html/rfc6749#section-5.1

will result in less bytes to be sent over the wire

…in terms of the cookie string. It seems that the library itself will also be slightly smaller, but I need to see.