Default node icon. For any node if its icon property is not defined, then default icon will be used. The icon property is a css class for the icon span. use icon for nodes. <span class="{icon}">...</span> The icon property can also be an object of the followin structure: { text : '' // string or function, html of the badge tooltip : '', // string or function, tooltip for the badge style : '', // style for the badge onClick : function // on click event badger } You can define it during object creation: let sidebar = new w2sidebar({ name : 'sidebar', icon : 'fa fa-start', nodes: [ { id: 'id-1', text: 'Level 1' }, { id: 'id-2', text: 'Level 2' }, { id: 'id-3', text: 'Level 3' } ] }); Or any time after the object has been created: w2ui.sidebar.icon = 'fa fa-star'; See also .nodes to see how to