Improve addition/substraction with units

[Tharit]

I think it could be really useful if the currently implemented unit handling (such as '+1 Monday') would be improved in a way that I could retrieve things like:

• the next/previous Monday only if the specified date is not a Monday
• the start of the next/previous week only if the specified date is not the beginning of a week (would require adding first_weekday from glibc locales)
• same for months and years..

[bigeasy]

Actually, you can get plus one Monday if today is not monday with the following:

var startOfWeek = tz(Date.now(), '-1 day', '+1 monday');

Going backwards...

var lastWeek = tz(Date.now(), '+1 day', '-1 monday');

When I'm able to get something via a recipe, I'm adverse to adding something more to the core. One of the goals of Timezone is to be a MicroJS library.

[Tharit]

Oh.. I must admit I didn't think of that, thanks. You're absolutely right, no need to add another way for something that's already possible - using Timezone for that very reason.

And now that I'm thinking about it, for months and years this should do the trick:

var startOfMonth = tz(tz(Date.now(),'%Y-%m-01'));
var nextMonth = tz(tz(Date.now(),'%Y-%m-01'),'+1 month');

Just the issue with weeks starting on locale dependant days remaining then. Probably not THAT relevant.

[bigeasy]

Yes. Exactly. I knew I had a solution for "last monday of the month", but I couldn't remember it.

var secondMonday = tz(tz(Date.now(),'%Y-%m-01'), '-1 day', '+2 mondays');
var lastMonday = tz(tz(Date.now(),'%Y-%m-01'), '+1 month', '-1 monday');

It is reassuring to know that people appreciate the design goals of Timezone. Thank you very much.