Common Utilities

The @ngrx-addons/common package provides shared utilities used by both persist-state and sync-state. You can also use them independently.

Key Filtering Operators

excludeKeys

An RxJS operator that removes specified keys from the emitted state object:

import { excludeKeys } from '@ngrx-addons/common';

state$.pipe(excludeKeys(['temporaryFlag', 'loading']));
// { count: 1, temporaryFlag: true, loading: false }
// → { count: 1 }

includeKeys

An RxJS operator that keeps only the specified keys:

import { includeKeys } from '@ngrx-addons/common';

state$.pipe(includeKeys(['count', 'name']));
// { count: 1, name: 'test', loading: false }
// → { count: 1, name: 'test' }

isEqual

A deep equality comparison function used internally by distinctUntilChanged to prevent unnecessary storage writes / broadcasts:

import { isEqual } from '@ngrx-addons/common';

isEqual({ a: 1, b: { c: 2 } }, { a: 1, b: { c: 2 } }); // true
isEqual({ a: 1 }, { b: 1 }); // false
isEqual([1, 2, 3], [1, 2, 3]); // true

Initialization Strategies

BeforeAppInit

Resolves immediately. State is rehydrated / synced before APP_INITIALIZER completes.

This is the default strategy for both persist-state and sync-state.

AfterAppInit

Resolves only after markAsInitialized() is called. Useful when your app initializers need the default state before rehydration:

import { AfterAppInit } from '@ngrx-addons/common';

// In your provider config
providePersistStore({
  strategy: AfterAppInit,
  states: [...],
});

// In your root component
@Component({ ... })
export class AppComponent {
  private readonly afterAppInit = inject(AfterAppInit);

  ngOnInit() {
    // Trigger rehydration after your initialization logic
    this.afterAppInit.markAsInitialized();
  }
}

The afterAppInitProvider is automatically included when you use providePersistStore or provideSyncStore.