Function preload

docs/index.js:17110–17170

(href, as, options)

  preconnectAs("preconnect", href, crossOrigin);
}
function preload(href, as, options) {
  previousDispatcher.L(href, as, options);
  var ownerDocument = globalDocument;
  if (ownerDocument && href && as) {
    var preloadSelector =
      'link[rel="preload"][as="' +
      escapeSelectorAttributeValueInsideDoubleQuotes(as) +
      '"]';
    "image" === as
      ? options && options.imageSrcSet
        ? ((preloadSelector +=
            '[imagesrcset="' +
            escapeSelectorAttributeValueInsideDoubleQuotes(
              options.imageSrcSet
            ) +
            '"]'),
          "string" === typeof options.imageSizes &&
            (preloadSelector +=
              '[imagesizes="' +
              escapeSelectorAttributeValueInsideDoubleQuotes(
                options.imageSizes
              ) +
              '"]'))
        : (preloadSelector +=
            '[href="' +
            escapeSelectorAttributeValueInsideDoubleQuotes(href) +
            '"]')
      : (preloadSelector +=
          '[href="' +
          escapeSelectorAttributeValueInsideDoubleQuotes(href) +
          '"]');
    var key = preloadSelector;
    switch (as) {
      case "style":
        key = getStyleKey(href);
        break;
      case "script":
        key = getScriptKey(href);
    }
    preloadPropsMap.has(key) ||
      ((href = assign(
        {
          rel: "preload",
          href:
            "image" === as && options && options.imageSrcSet ? void 0 : href,
          as: as
        },
        options
      )),
      preloadPropsMap.set(key, href),
      null !== ownerDocument.querySelector(preloadSelector) ||
        ("style" === as &&
          ownerDocument.querySelector(getStylesheetSelectorFromKey(key))) ||
        ("script" === as &&
          ownerDocument.querySelector(getScriptSelectorFromKey(key))) ||
        ((as = ownerDocument.createElement("link")),
        setInitialProperties(as, "link", href),
        markNodeAsHoistable(as),