http://flowplayer.org/tools/forum/70/50369

dateinput.js

/* workaround for 2 bugs related to jQuery Tools Dateinput:
 * 1) the initial value is wrongly set
 * 2) "data-" attributes presents on the target input get wiped out
 */

  $(":date[data-backend]").each(function() {
    var backend_attr = $(this).attr("data-backend");
    var value = $(backend_attr).val();
    var year  = parseInt(value.substring(0, 4), 10);
    var month = parseInt(value.substring(4, 6), 10) - 1;
    var day   = parseInt(value.substring(6, 8), 10);
    var init_date = new Date(year, month, day);
    $(this).dateinput({
      firstDay: 1,
      format: "dd-mm-yyyy",
      selectors: true,
    })
    .attr("data-backend", backend_attr)
    .change(function() {
      var isoDate = $(this).data("dateinput").getValue('yyyymmdd');
      var backend = $(this).attr('data-backend');
      $(backend).val(isoDate);
    }).data("dateinput").setValue(init_date);
  });


// the desired behavior:

  $(":date[data-backend]").each(function() {
    $(this).dateinput({
      firstDay: 1,
      format: "dd-mm-yyyy",
      selectors: true
    }).change(function() {
      var isoDate = $(this).data("dateinput").getValue('yyyymmdd');
      var backend = $(this).attr('data-backend');
      $(backend).val(isoDate);
    });
  });

/*
the reference html:

  <input type="date" data-backend="#dp_start" data-value="20101101" value="2010-11-01" />
  <input type="date" data-backend="#dp_end" data-value="20101130" value="20101130" />
  <input id="dp_start" type="hidden" name="startDate" value="20101101" />
  <input id="dp_end" type="hidden" name="endDate" value="20101130" />
*/