Check out this plugin:
moment-countdown is a tiny moment.js plugin that integrates with Countdown.js. The file is here.
How it works?
//from then until now
moment("1982-5-25").countdown().toString(); //=> '30 years, 10 months, 14 days, 1 hour, 8 minutes, and 14 seconds'
//accepts a moment, JS Date, or anything parsable by the Date constructor
moment("1955-8-21").countdown("1982-5-25").toString(); //=> '26 years, 9 months, and 4 days'
//also works with the args flipped, like diff()
moment("1982-5-25").countdown("1955-8-21").toString(); //=> '26 years, 9 months, and 4 days'
//accepts all of countdown's options
moment().countdown("1982-5-25", countdown.MONTHS|countdown.WEEKS, NaN, 2).toString(); //=> '370 months, and 2.01 weeks'