Function ɵɵdeferHydrateWhen

packages/core/src/defer/instructions.ts:300–340

(rawValue: unknown)

 * @codeGenApi
 */
export function ɵɵdeferHydrateWhen(rawValue: unknown) {
  const lView = getLView();
  const tNode = getSelectedTNode();

  if (ngDevMode) {
    trackTriggerForDebugging(lView[TVIEW], tNode, 'hydrate when <expression>');
  }

  if (!shouldAttachTrigger(TriggerType.Hydrate, lView, tNode)) return;

  // TODO(incremental-hydration): audit all defer instructions to reduce unnecessary work by
  // moving function calls inside their relevant control flow blocks
  const bindingIndex = nextBindingIndex();
  const tView = getTView();
  const hydrateTriggers = getHydrateTriggers(tView, tNode);
  hydrateTriggers.set(DeferBlockTrigger.When, null);

  if (bindingUpdated(lView, bindingIndex, rawValue)) {
    if (typeof ngServerMode !== 'undefined' && ngServerMode) {
      // We are on the server and SSR for defer blocks is enabled.
      triggerDeferBlock(TriggerType.Hydrate, lView, tNode);
    } else {
      const injector = lView[INJECTOR];
      const prevConsumer = setActiveConsumer(null);
      try {
        const value = Boolean(rawValue); // handle truthy or falsy values
        if (value === true) {
          // The `when` condition has changed to `true`, trigger defer block loading
          // if the block is either in initial (nothing is rendered) or a placeholder
          // state.
          const lDetails = getLDeferBlockDetails(lView, tNode);
          const ssrUniqueId = lDetails[SSR_UNIQUE_ID]!;
          ngDevMode && assertSsrIdDefined(ssrUniqueId);
          triggerHydrationFromBlockName(injector, ssrUniqueId);
        }
      } finally {
        setActiveConsumer(prevConsumer);
      }
    }
  }
}

/**
 * Specifies that hydration never occurs.