You can manage this by providing a template object with a custom render function to the NavBarContainer:
var navEl = document.getElementById('navbar');
var navBar = new WinJS.UI.NavBar(navEl);
var containerEl = document.createElement('div');
navEl.appendChild(containerEl);
var template = {
render: function (item, navbarCommandEl) {
navbarCommandEl.classList.add(item.state);
}
};
var navBarContainer = new WinJS.UI.NavBarContainer(containerEl, {
template: template
});
var data = [
{ label: 'Test 1', icon: 'world', state: 'bold' },
{ label: 'Test 2', icon: 'world', state: 'normal'},
{ label: 'Test 3', icon: 'world', state: 'underlined' }
]
var itemList = new WinJS.Binding.List(data);
navBarContainer.data = itemList;
Hope that helps! :)