A tiny module to calculate the epidemiological week (also known as "epi week" or "CDC week") for any given date.
var epi = require('epi-week');
epi(new Date(2012, 11, 29)); // returns { week: 52, year: 2012 }
epi(new Date(2012, 11, 30)); // returns { week: 1, year: 2013 }
epi(new Date(2015, 0, 1)); // returns { week: 53, year: 2014 }
$ npm install epi-week
This package is in its infancy, use with caution.