var year=parseInt(prompt("请输入员工入职年份"));
   var mouth=parseInt(prompt("请输入员工入职月份"));
   var date=parseInt(prompt("请输入员工入职时间"));

  function st() {
   var today=new Date();
   today.setFullYear(year);
   today.setMonth(mouth-1);
   today.setDate(date);
      var df=new Date(year+3,mouth-1,date);
      document.write("该员工入职日期是"+year+"-"+mouth+"月"+"-"+date+"日"+"<br/>");
      document.write("该员工合同到期日期是"+df.getFullYear()+"-"+(df.getMonth()+1)+"月"+"-"+df.getDate()+"日");
}
   st(year,mouth,date);