How to add the Author/Edit mode condition in sightly/HTL for class attribute values.?

I have a HTML snippet as below.

 <div id="mydivid" class="abcd xyz myclass"> .... ... </div> 

I have wrote it in below way. but it doesn't shows the entire dive in wcmmode=disabled.

<div data-sly-test.editor="${wcmmode.edit || wcmmode.design}"> <div id="mydivid" class="abcd xyz myclass"> </div> .... ... <div data-sly-test.editor="${wcmmode.edit || wcmmode.design}"> </div> </div> 

Is there any way to add "myclass" value to the class attribute alone only in author mode alone and not in preview or disabled mode of AEM page.