Function addServerStyles

packages/platform-browser/src/dom/shared_styles_host.ts:65–92

* Searches a DOM document's head element for style elements with a matching application * identifier attribute (`ng-app-id`) to the provide identifier and adds usage records for each. * @param doc An HTML DOM document instance. * @param appId A string containing an Angular application identifer.

(
  doc: Document,
  appId: string,
  inline: Map<string, UsageRecord<HTMLStyleElement>>,
  external: Map<string, UsageRecord<HTMLLinkElement>>,
)

 * @returns Whether or not styles were added.
 */
function addServerStyles(
  doc: Document,
  appId: string,
  inline: Map<string, UsageRecord<HTMLStyleElement>>,
  external: Map<string, UsageRecord<HTMLLinkElement>>,
): boolean {
  const elements = doc.head?.querySelectorAll<HTMLStyleElement | HTMLLinkElement>(
    `style[${APP_ID_ATTRIBUTE_NAME}="${appId}"],link[${APP_ID_ATTRIBUTE_NAME}="${appId}"]`,
  );

  if (!elements || elements.length === 0) return false;

  for (const styleElement of elements) {
    styleElement.removeAttribute(APP_ID_ATTRIBUTE_NAME);
    if (styleElement instanceof HTMLLinkElement) {
      // Only use filename from href
      // The href is build time generated with a unique value to prevent duplicates.
      external.set(styleElement.href.slice(styleElement.href.lastIndexOf('/') + 1), {
        usage: 0,
        elements: [styleElement],
      });
    } else if (styleElement.textContent) {
      inline.set(styleElement.textContent, {usage: 0, elements: [styleElement]});
    }
  }

  return true;
}

/**
 * Creates a `link` element for the provided external style URL.