Date.js library for parsing JS dates. From https://code.google.com/p/datejs/

date.js

Date.today()                    // Returns today's date, with time set to 00:00 (start of day).

Date.today().next().friday()    // Returns the date of the next Friday.
Date.today().last().monday()    // Returns the date of the previous Monday.

new Date().next().march()       // Returns the date of the next March.
new Date().last().week()        // Returns the date one week ago. 

Date.today().is().friday()      // Returns true|false if the day-of-week matches.
Date.today().is().fri()         // Abbreviated day names. 

Date.today().is().november()    // Month names.
Date.today().is().nov()         // Abbreviated month names.

Date.today().is().weekday()     // Is today a weekday?

Date.today().addDays(1)         // Add one day (+1).
Date.today().addMonths(-3)      // Subtract three months (-3).

Date.today().add(1).day()       // Add one (+1) day. Supports all date parts (year, month, day, hour, minute, second, millisecond, and weeks)
Date.today().add(-3).months()   // Subtract three (-3) months.

(1).day().fromNow()             // One (1) day from now. 
(3).months().ago()              // Three (3) months ago.

var n = 6;
n.months().fromNow()            // Six (6) months from now.

Date.monday()                   // Returns Monday of the current week.
Date.mon()                      // Abbreviated version of Date.monday()

Date.march()                    // Returns March 1st of this year.
Date.mar()                      // Abbreviated version of Date.march()

Date.today().first().thursday() // Returns the first Thursday of the current month.
Date.today().second().thursday()// Returns the second Thursday of the current month.

Date.march().third().thursday() // Returns the third Thursday in March of the current year.
Date.october().fourth().sunday()// Returns the fourth Sunday in October.

Date.today().fifth().sunday()   // Returns the fifth Sunday in the current month, or throws a RangeError exception if there are not 5 Sundays in the current month.
Date.october().final().sunday() // Returns the final Sunday in October.

Date.january().first().monday() // Returns the first Monday of the current year.
Date.december().final().friday()// Returns the last Friday of the current year.

Date.today().at("6:15pm");      // Returns todays date at 6:15pm.

var time = {hour:18, minute:15};
Date.today().at(time);          // Set time with a config object.

var birthDayParty = {month: 1, day: 20, hour: 20, minute: 30};
Date.today().set(birthDayParty);// Set date and time with a config object.