[рони]

insider999,

var holidays = {2016 : {
  "0" : [1, 2, 3, 4, 5, 6, 7, 8],
  "1" : [23],
  "2" : [8],
  "4" : [1, 9],
  "5" : [12],
  "11" : [4]
  }},
 UserDays = 52, dateFromUserDate = new Date("1/5/2016");

  for (var i = 0; i < UserDays; i++) {
  var day = dateFromUserDate.getDate();
  dateFromUserDate.setDate(day+1);
  var fullyear = dateFromUserDate.getFullYear();
  var month = dateFromUserDate.getMonth();
  day = dateFromUserDate.getDate();
  holidays[fullyear] && holidays[fullyear][month] && holidays[fullyear][month].indexOf(day) !== -1 && --i
  }
 alert(dateFromUserDate.toLocaleDateString());