Function shouldAttachRegularTrigger

packages/core/src/defer/triggering.ts:615–638

* Defines whether a regular trigger logic (e.g. "on viewport") should be attached * to a defer block. This function defines a condition, which mutually excludes * `deferOn*` and `deferHydrateOn*` triggers, to make sure only one of the trigger * types is active for a block with the current state.

(lView: LView, tNode: TNode)

 * types is active for a block with the current state.
 */
function shouldAttachRegularTrigger(lView: LView, tNode: TNode): boolean {
  const injector = lView[INJECTOR];

  const tDetails = getTDeferBlockDetails(lView[TVIEW], tNode);
  const incrementalHydrationEnabled = isIncrementalHydrationEnabled(injector);
  const _hasHydrateTriggers = hasHydrateTriggers(tDetails.flags);

  // On the server:
  if (typeof ngServerMode !== 'undefined' && ngServerMode) {
    // Regular triggers are activated on the server when:
    //  - Either Incremental Hydration is *not* enabled
    //  - Or Incremental Hydration is enabled, but a given block doesn't have "hydrate" triggers
    return !incrementalHydrationEnabled || !_hasHydrateTriggers;
  }

  // On the client:
  const lDetails = getLDeferBlockDetails(lView, tNode);
  const wasServerSideRendered = lDetails[SSR_UNIQUE_ID] !== null;

  if (_hasHydrateTriggers && wasServerSideRendered && incrementalHydrationEnabled) {
    return false;
  }
  return true;
}

/**
 * Retrives a Defer Block's list of hydration triggers