in styles/docfx.js [877:896]
function initTabGroup(element) {
var group = {
independent: element.hasAttribute('data-tab-group-independent'),
tabs: []
};
var li = element.firstElementChild.firstElementChild;
while (li) {
var a = li.firstElementChild;
a.setAttribute(contentAttrs.name, 'tab');
var dataTab = a.getAttribute('data-tab').replace(/\+/g, ' ');
a.setAttribute('data-tab', dataTab);
var section = element.querySelector("[id=\"" + a.getAttribute('aria-controls') + "\"]");
var tab = new Tab(li, a, section);
group.tabs.push(tab);
li = li.nextElementSibling;
}
element.setAttribute(contentAttrs.name, 'tab-group');
element.tabGroup = group;
return group;
}