in eng/common/docgeneration/templates/matthews/styles/main.js [135:142]
$(versionselector).change(function () {
targetVersion = $(this).val()
url = WINDOW_CONTENTS.slice()
url[6] = targetVersion
var targetUrl = url.join('/')
httpGetAsyncFallbackOnFail(targetUrl, (unused) => window.location.href = url.join('/'),
(failureStatus) => window.location.href = getPackageUrl(SELECTED_LANGUAGE, packageName, targetVersion))
});