jQuery Birthdate Picker

form.haml

= javascript_include_tag 'jquery/jquery-birthday-picker'
:javascript
  $(document).ready(function() {
    $('.birth_date_selection').birthdayPicker({monthFormat: 'long', minAge: 18, defaultDate: '15-05-2015'});
  });
= form_for @user do |user|
  .birth_date_selection
    = user.date_select(:birth_date, order: [:month, :day, :year])

jquery.birthdate_picker.js

$(function(e) {
  var t = {
      number: ['01', '02', '03', '04', '05', '06', '07', '08', '09', '10', '11', '12'],
      short: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
      long: ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December']
    },
    n = new Date,
    r = n.getFullYear(),
    i = n.getMonth() + 1,
    s = n.getDate();
  generateBirthdayPicker = function(n, s) {
    var o = e("<fieldset class='birthdayPicker'></fieldset>").addClass(s.wrapperClass),
      u = $("select[id*='birth_date_1i']").addClass(s.sizeClass).empty(),
      a = $("select[id*='birth_date_2i']").addClass(s.sizeClass).empty(),
      f = $("select[id*='birth_date_3i']").addClass(s.sizeClass).empty();
    $birthday = e("<input class='birthDay' name='birthDay' type='hidden'/>");
    if (s.placeholder) {
      e("<option value=''>Year</option>").appendTo(u);
      e("<option value=''>Month</option>").appendTo(a);
      e("<option value=''>Day</option>").appendTo(f)
    }
    if (s.dateFormat == 'bigEndian') {
      o.append(u).append(a).append(f)
    } else if (s.dateFormat == 'littleEndian') {
      o.append(f).append(a).append(u)
    } else {
      o.append(a).append(f).append(u)
    }
    var l = r - s.minAge;
    var c = r - s.maxAge;
    if (s.maxYear != r && s.maxYear > r) {
      l = s.maxYear;
      c = c + (s.maxYear - r)
    }
    for (var h = l; h >= c; h--) {
      e('<option></option>').attr('value', h).text(h).appendTo(u)
    }
    for (var h = 0; h <= 11; h++) {
      e('<option></option>').attr('value', h + 1).text(t[s.monthFormat][h]).appendTo(a)
    }
    for (var h = 1; h <= 31; h++) {
      var p = h < 10 ? '0' + h : h;
      e('<option></option>').attr('value', h).text(p).appendTo(f)
    }
    if (s.defaultDate) {
      var d = new Date(s.defaultDate);
      console.log(d);
      u.val(d.getFullYear());
      a.val(d.getMonth() + 1);
      f.val(d.getDate())
    }
    o.append($birthday);
    n.append(o);
    o.on('change', function() {
      selectedYear = parseInt(u.val(), 10), selectedMonth = parseInt(a.val(), 10), selectedDay = parseInt(f.val(), 10);
      var n = a.children(':last').val();
      if (selectedYear > r) {
        if (n > i) {
          while (n > i) {
            a.children(':last').remove();
            n--
          }
        }
      } else {
        while (n < 12) {
          e('<option></option>').attr('value', parseInt(n) + 1).text(t[s.monthFormat][n]).appendTo(a);
          n++
        }
      }
      var o = f.children(':last').val();
      var l = (new Date(selectedYear, selectedMonth, 0)).getDate();
      if (o > l) {
        while (o > l) {
          f.children(':last').remove();
          o--
        }
      } else if (o < l) {
        while (o < l) {
          var c = parseInt(o) + 1;
          var h = c < 10 ? '0' + c : c;
          e('<option></option>').attr('value', c).text(h).appendTo(f);
          o++
        }
      }
      if (selectedYear * selectedMonth * selectedDay != 0) {
        if (selectedMonth < 10) selectedMonth = '0' + selectedMonth;
        if (selectedDay < 10) selectedDay = '0' + selectedDay;
        hiddenDate = selectedYear + '-' + selectedMonth + '-' + selectedDay;
        e(this).find('input[name=birthDay]').val(hiddenDate)
      }
    })
  };
  e.fn.birthdayPicker = function(t) {
    return this.each(function() {
      var n = e.extend(e.fn.birthdayPicker.defaults, t);
      generateBirthdayPicker(e(this), n)
    })
  };
  e.fn.birthdayPicker.defaults = {
    maxAge: 100,
    minAge: 0,
    maxYear: r,
    dateFormat: 'middleEndian',
    monthFormat: 'number',
    placeholder: true,
    defaultDate: false,
    sizeClass: '', // custom class for proper sizing
    wrapperClass: 'form-inline'
  }
}(jQuery))