var monthtext=['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sept','Oct','Nov','Dec'];

function populatedropdown(dayfield, monthfield, yearfield){
  var today=new Date()
  var dayfield=document.getElementById(dayfield)
  var monthfield=document.getElementById(monthfield)
  var yearfield=document.getElementById(yearfield)
  
  for (var i=0; i<31; i++)
    dayfield.options[i]=new Option(i+1, i+1)
    dayfield.options[today.getDate()]=new Option(today.getDate(), today.getDate(), true, true) //select today's day
    
  for (var m=0; m<12; m++)
    monthfield.options[m]=new Option(monthtext[m], monthtext[m])
    monthfield.options[today.getMonth()]=new Option(monthtext[today.getMonth()], monthtext[today.getMonth()], true, true) //select today's month
  
  
  var thisyear=today.getFullYear()
  
  for (var y=0; y<20; y++){
    yearfield.options[y]=new Option(thisyear, thisyear)
    thisyear+=1
  }
  yearfield.options[0]=new Option(today.getFullYear(), today.getFullYear(), true, true) //select today's year
}