get the week number for a date
Calculate the week number for a given date
This module extends the Date.prototype, I know don't do this, whatever. If you need week numbers I think it's clean this way.
By default weeks are numberd based on 1970-1-5 (the first monday of 1970, as this presents the first week.
require'week_no';1971 0 5weekNo # => 521972 0 5weekNo # => 104
Return a the number of weeks since
With npm do:
npm install week_no