function importHref()

in gr-editor/gr-editor.js [43:96]

• 18 lines of code
• 4 McCabe index (conditional complexity)

function importHref(href, onload, onerror) {
  let link =
      /** @type {HTMLLinkElement} */
      (document.head.querySelector('link[href="' + href + '"][import-href]'));
  if (!link) {
    link = /** @type {HTMLLinkElement} */ (document.createElement('link'));
    link.setAttribute('rel', 'import');
    link.setAttribute('href', href);
    link.setAttribute('import-href', '');
  }
  // NOTE: the link may now be in 3 states: (1) pending insertion,
  // (2) inflight, (3) already loaded. In each case, we need to add
  // event listeners to process callbacks.
  const cleanup = function() {
    link.removeEventListener('load', loadListener);
    link.removeEventListener('error', errorListener);
  };
  const loadListener = function(event) {
    cleanup();
    // In case of a successful load, cache the load event on the link so
    // that it can be used to short-circuit this method in the future when
    // it is called with the same href param.
    link.__dynamicImportLoaded = true;
    if (onload) {
      whenImportsReady(() => {
        onload(event);
      });
    }
  };
  const errorListener = function(event) {
    cleanup();
    // In case of an error, remove the link from the document so that it
    // will be automatically created again the next time `importHref` is
    // called.
    if (link.parentNode) {
      link.parentNode.removeChild(link);
    }
    if (onerror) {
      whenImportsReady(() => {
        onerror(event);
      });
    }
  };
  link.addEventListener('load', loadListener);
  link.addEventListener('error', errorListener);
  if (link.parentNode == null) {
    document.head.appendChild(link);
    // if the link already loaded, dispatch a fake load event
    // so that listeners are called and get a proper event argument.
  } else if (link.__dynamicImportLoaded) {
    link.dispatchEvent(new Event('load'));
  }
  return link;
}