There is no javaScript API that allows you do this directly.

 

However if you are familar with JavaScript, you can populate the RichDropDownList using javaScript easily.

 

Here is the html code of FormatBlock dropdown. 

 

To add your own span item, you need to follow the steps below.

 

1. Get FormatBlock dropdown by ID.

 

2. Create your span item and append it to FormatBlock dropdown object (using appendChild method).

 

3. Set attribute to your span item (using setAttibute method).

<span class="CuteEditorDropDown" id="CE_Editor1_IDformatblock" Command="FormatBlock" onchange="CuteEditor_DropDownCommand(this,'FormatBlock')" RichHideFirstItem="true" RenderItemBorder="true" _IsRichDropDown="True" style="display:inline-block;width:70px;height:20px;">

<span val="" selected="True" html="Paragraph" txt="Paragraph"></span>

<span val="&lt;P>" html="Normal" txt="Normal"></span>
<span val="&lt;H1>" html="&lt;b style='font-size:24pt'>Heading 1&lt;/b>" txt="Heading 1"></span>
<span val="&lt;H2>" html="&lt;b style='font-size:18pt'>Heading 2&lt;/b>" txt="Heading 2"></span>
<span val="&lt;H3>" html="&lt;b style='font-size:15pt'>Heading 3&lt;/b>" txt="Heading 3"></span>
<span val="&lt;H4>" html="&lt;b style='font-size:12pt'>Heading 4&lt;/b>" txt="Heading 4"></span>
<span val="&lt;H5>" html="&lt;b style='font-size:9pt'>Heading 5&lt;/b>" txt="Heading 5"></span>
<span val="&lt;H6>" html="&lt;b style='font-size:7pt'>Heading 6&lt;/b>" txt="Heading 6"></span>
<span val="&lt;Address>" html="Address" txt="Address"></span>
<span val="&lt;MENU>" html="Menu List" txt="Menu List"></span>
<span val="&lt;PRE>" html="Formatted" txt="Formatted"></span>
<span val="&lt;DT>" html="Definition Term" txt="Definition Term"></span>

</span>