Function appendPreloadToMetadata

packages/angular/ssr/src/routes/ng-routes.ts:362–387

* Appends preload information to the metadata object based on the specified entry-point and chunk mappings. * * This function extracts preload data for a given entry-point from the provided chunk mappings. It adds the * corresponding browser bundles to the metadata's preload list, ensuring no dup

(
  entryName: string,
  entryPointToBrowserMapping: EntryPointToBrowserMapping,
  metadata: ServerConfigRouteTreeNodeMetadata,
)

 * preloads to a predefined maximum.
 */
function appendPreloadToMetadata(
  entryName: string,
  entryPointToBrowserMapping: EntryPointToBrowserMapping,
  metadata: ServerConfigRouteTreeNodeMetadata,
): void {
  const existingPreloads = metadata.preload ?? [];
  if (!entryPointToBrowserMapping || existingPreloads.length >= MODULE_PRELOAD_MAX) {
    return;
  }

  const preload = entryPointToBrowserMapping[entryName];
  if (!preload?.length) {
    return;
  }

  // Merge existing preloads with new ones, ensuring uniqueness and limiting the total to the maximum allowed.
  const combinedPreloads: Set<string> = new Set(existingPreloads);
  for (const href of preload) {
    combinedPreloads.add(href);
    if (combinedPreloads.size === MODULE_PRELOAD_MAX) {
      break;
    }
  }

  metadata.preload = Array.from(combinedPreloads);
}

/**
 * Handles SSG (Static Site Generation) routes by invoking `getPrerenderParams` and yielding