Here you can find the source of subtractNow(b)
Date.prototype.subtractNow = function(b) { return this.subtract(new Date()) } Date.prototype.subtract = function(b) { var delta = this.getTime()-b.getTime() return new Date(0,0,0,delta/1000/60/60,(delta/1000/60)%60,(delta/1000)%60) }
Date.prototype.subtract = function(b) { var delta = this.getTime()-b.getTime() return new Date(0,0,0,delta/1000/60/60,(delta/1000/60)%60,(delta/1000)%60)