jquery UI dialog: how to initialize without a title bar?

I think that the best solution is to use the option dialogClass.

An extract from jquery UI docs:

during init : $('.selector').dialog({ dialogClass: 'noTitleStuff' });

or if you want after init. :

$('.selector').dialog('option', 'dialogClass', 'noTitleStuff');

So i created some dialog with option dialogClass='noTitleStuff' and the css like that:

.noTitleStuff .ui-dialog-titlebar {display:none}

too simple !! but i took 1 day to think why my previous id->class drilling method was not working. In fact when you call .dialog() method the div you transform become a child of another div (the real dialog div) and possibly a 'brother' of the titlebar div, so it's very difficult to try finding the latter starting from former.

I figured out a fix for dynamically removing the title bar.

$("#example").dialog(dialogOpts);
// remove the title bar
$(".ui-dialog-titlebar").hide();

This will remove all elements with the class 'ui-dialog-titlebar' after the dialog box is rendered.

I believe you can hide it with CSS:

.ui-dialog-titlebar {
    display: none;
}

Alternatively, you can apply this to specific dialogs with the dialogClass option:

$( "#createUserDialog" ).dialog({
    dialogClass: "no-titlebar"
});

.no-titlebar .ui-dialog-titlebar {
    display: none;
}

Check out "Theming" the Dialog. The above suggestion makes use of the dialogClass option, which appears to be on it's way out in favor of a new method.

Have you tried solution from jQuery UI docs? https://api.jqueryui.com/dialog/#method-open

As it say you can do like this...

In CSS:

.no-titlebar .ui-dialog-titlebar {
  display: none;
}

In JS:

$( "#dialog" ).dialog({
  dialogClass: "no-titlebar"
});

This worked for me

 open: function(event, ui) {
            $(".ui-dialog-titlebar", $(this).parent())
              .hide();

Full

$speedbump.dialog({
  dialogClass: 'speedbump-container',
  autoOpen: false,
  closeOnEscape: false,
  modal: true,
  resizable: false,
  draggable: false,
  create: function () {        
      $speedbump
        .closest('.ui-dialog')
        .attr('id', 'speedbump-container');
  },
  open: function(event, ui) {
    $(".ui-dialog-titlebar", $(this).parent())
      .hide();
}