in antora/supplemental-ui/js/tabsBehavior.js [29:42]
find('li', tabs).forEach(function (tab, idx) {
var id = (tab.querySelector('a[id]') || tab).id
if (!id) return
var pane = getPane(id, tabset)
if (!idx) first = { tab: tab, pane: pane }
if (!active && hash === '#' + id && (active = true)) {
tab.classList.add('is-active')
if (pane) pane.classList.add('is-active')
} else if (!idx) {
tab.classList.remove('is-active')
if (pane) pane.classList.remove('is-active')
}
tab.addEventListener('click', activateTab.bind({ tabset: tabset, tab: tab, pane: pane }))
})