OnClientLoad
The OnClientLoad client-side event occurs when the RadRibbonBar is first loaded and fully initialized on the client. The event handler receives a single parameter: the instance of the ribbonbar firing the event.
function OnClientLoad(sender, args) {
var ribbonbar = $find("RadRibbonBar1");
var tab0 = ribbonbar.get_tabs().getTab(0);
//tab0.set_text("NewTab0");
var group0 = tab0.get_groups().getGroup(0);
//group0.set_text("NewGroup0");
var item0 = group0.get_items().getItem(0);
//returns the text of the first button in the first group of the first tab
alert(item0.get_text());
}