Bootstrap Datepicker Set Default Date Not Working

bootstrap datepicker today as default

This should work:

$("#datepicker").datepicker("setDate", new Date());

And for autoclose (fiddle):

$('#datepicker').datepicker({
        "setDate": new Date(),
        "autoclose": true
});

jQuery > datepicker API

Set default date for bootstrap datepicker

Use formate: instead of dateFormat:

<script type="text/javascript" >
    function toggle_dp() {
        $("#myModal").modal("show");
        $("#datepicker").datepicker({
          format: 'dd/mm/yy',
          changeMonth: true,
          changeYear: true,
          defaultDate: new Date(toMMDDYYYY(startDate))
        });

    }

function toMMDDYYYY(date) {
            var datePart = date.split("/");
            var MMDDYYYY = [datePart[1], datePart[0],datePart[2]].join('/');
            return MMDDYYYY
        }
</script>

Bootstrap Datetime picker dynamic default date not working

$('#current_session_date').datetimepicker({
  defaultDate: defaultD,
});

This creates the datetimepicker with an initial value, so doesn't work if the datetimepicker already exists.

You either need to call date([newDate]) to update it in place (you'll need to initialise it elsewhere) or destroy() it when the modal is closed, allowing you to remake it with a new initial value.

Bootstrap Datepicker - Set default picker date, NOT display value

Here it is:

$('.datepicker').datepicker({
    defaultViewDate: {year:2000, month:0, day:1},
});

And the js Fiddle:

https://jsfiddle.net/mb34zwg3/

Set Default Date Bootstrap Datepicker

You can do:

$('#dob').datepicker('setDate', new Date(2006, 11, 24));
$('#dob').datepicker('update');
$('#dob').val('');

Fiddle Demo

How to put a default date in bootstrap datetimepicker

Just set the value after setting up the datetimepicker:

$('.form_date').datetimepicker({
  weekStart: 1,
  todayBtn: 1,
  autoclose: 1,
  todayHighlight: 1,
  startView: 2,
  minView: 2,
  forceParse: 0,
});
$('#dtp_input2').val(Date());