@ngrx/store meta reducer that prevents state from being mutated.
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Latest commit 4586d66 Jun 5, 2018



npm version CircleCI

ngrx-store-freeze is a meta-reducer that prevents state from being mutated

  • Recursively freezes the current state, the dispatched action payload if provided and the new state.
  • When mutation occurs, an exception will be thrown.
  • Should be used only in development to ensure that the state remains immutable.


npm i --save-dev ngrx-store-freeze


yarn add ngrx-store-freeze --dev


import { StoreModule, MetaReducer, ActionReducerMap } from '@ngrx/store';
import { storeFreeze } from 'ngrx-store-freeze';
import { environment } from '../environments/environment'; // Angular CLI environment

export interface State {
  // reducer interfaces

export const reducers: ActionReducerMap<State> = {
  // reducers

export const metaReducers: MetaReducer<State>[] = !environment.production ? [storeFreeze]: [];

  imports: [
    StoreModule.forRoot(reducers, { metaReducers }),
export class AppModule {}

Additional Documentation


redux-freeze - Redux middleware that prevents state from being mutated
Attila Egyed - The original maintainer of this project