Function preconnectAs

docs/index.js:17083–17101

(rel, href, crossOrigin)

}
var globalDocument = "undefined" === typeof document ? null : document;
function preconnectAs(rel, href, crossOrigin) {
  var ownerDocument = globalDocument;
  if (ownerDocument && "string" === typeof href && href) {
    var limitedEscapedHref =
      escapeSelectorAttributeValueInsideDoubleQuotes(href);
    limitedEscapedHref =
      'link[rel="' + rel + '"][href="' + limitedEscapedHref + '"]';
    "string" === typeof crossOrigin &&
      (limitedEscapedHref += '[crossorigin="' + crossOrigin + '"]');
    preconnectsSet.has(limitedEscapedHref) ||
      (preconnectsSet.add(limitedEscapedHref),
      (rel = { rel: rel, crossOrigin: crossOrigin, href: href }),
      null === ownerDocument.querySelector(limitedEscapedHref) &&
        ((href = ownerDocument.createElement("link")),
        setInitialProperties(href, "link", rel),
        markNodeAsHoistable(href),
        ownerDocument.head.appendChild(href)));
  }
}
function prefetchDNS(href) {
  previousDispatcher.D(href);
  preconnectAs("dns-prefetch", href, null);