rrule.js
JS library for working with recurrence rules for calendar dates
JavaScript library for working with recurrence rules for calendar dates as defined in the iCalendar RFC and more. rrule.js supports recurrence rules as defined in the iCalendar RFC, with a few important differences. It is a partial port of the rrule module from the excellent python-dateutil library. On top of that, it supports parsing and serialization of recurrence rules from and to natural language.