setActive()
sets an active tab
setActive(id: string): void;
Parameters:
id: string- the id of a tab
Example
const tabbar = new dhx.Tabbar("tabbar_container", {
    mode: "top",            
    views:[
        { id: "1", tab: "tab-1", css:"panel flex"},
        { id: "2", tab: "tab-2", css:"panel flex"},
        { id: "3", tab: "tab-3", css:"panel flex"},
        { id: "4", tab: "tab-4", css:"panel flex"}
    ]
});
tabbar.setActive("2");
Related sample: Tabbar. Set active