Some useful date functions for Javascript

date_support.js

Date.today = function() {
  return (new Date()).beginningOfDay();
}

Date.prototype.beginningOfDay = function() {
  var result = new Date(this);
  result.setHours(0);
  result.setMinutes(0);
  result.setSeconds(0);
  result.setMilliseconds(0);
  return result;
}

Date.prototype.isPast = function() {
  return this.beginningOfDay().getTime() < Date.today().getTime();
}

Date.prototype.isToday = function() {
  return this.beginningOfDay().getTime() == Date.today().getTime();
}

Date.prototype.isFuture = function() {
  return this.beginningOfDay().getTime() > Date.today().getTime();
}

Date.prototype.isWeekend = function(weekends) {
  weekends = weekends || [0, 6];
  return $.inArray(this.getDay(), weekends) >= 0
}

Date.prototype.isWeekday = function(weekends) {
  return !this.isWeekend(weekends);
}