**Course Title:** Building Cross-Platform Mobile Applications with Ionic **Section Title:** State Management in Ionic Applications **Topic:** Using NgRx for Angular, Redux for React, or Vuex for Vue. **Overview** =============== In the previous topic, we introduced state management concepts in mobile apps. Now, we will dive deeper into specific state management libraries for each of the frameworks supported by Ionic: NgRx for Angular, Redux for React, and Vuex for Vue. These libraries provide a robust and scalable way to manage global state in your applications. ### NgRx for Angular **What is NgRx?** --------------- NgRx is a state management library for Angular applications inspired by Redux. It provides a single source of truth for your application's state and enables predictable and debuggable behavior. **Key Concepts** * **Store**: The central location that holds the entire state of your application. * **Actions**: Payloads that trigger state changes. * **Reducers**: Pure functions that handle actions and update the state. * **Selectors**: Functions that select a portion of the state and return it as an observable. **Example Usage** ```typescript import { Action, createReducer, createSelector, select } from '@ngrx/store'; import { Component, OnDestroy, OnInit } from '@angular/core'; // Define the action types export const LOAD_DATA = '[App] Load Data'; export const UPDATE_DATA = '[App] Update Data'; // Create the actions export class LoadData implements Action { readonly type = LOAD_DATA; } // Create the reducer const initialState = {}; const appReducer = createReducer(initialState, { [LOAD_DATA]: (state, action) => ({ ...state, data: action.payload }), }); // Create a selector to get the data export const selectData = createSelector( (state: any) => state.data, (data) => data ); @Component({ selector: 'app-example', template: '<p>Example Component</p>', }) export class ExampleComponent implements OnDestroy, OnInit { data$: Observable<any>; constructor(private store: Store<any>) { this.data$ = this.store.pipe(select(selectData)); } ngOnInit() { this.store.dispatch(new LoadData()); } ngOnDestroy() {} } ``` For more information about NgRx, visit [ngrx.io](https://ngrx.io/). ### Redux for React **What is Redux?** ----------------- Redux is a predictable state container for JavaScript applications. It provides a single source of truth for your application's state and enables predictable and debuggable behavior. **Key Concepts** * **Store**: The central location that holds the entire state of your application. * **Actions**: Payloads that trigger state changes. * **Reducers**: Pure functions that handle actions and update the state. * **Dispatch**: The function that sends actions to the store. **Example Usage** ```javascript import { createStore, combineReducers } from 'redux'; import { Provider } from 'react-redux'; import { applyMiddleware } from 'redux-thunk'; // Define the action types export const LOAD_DATA = 'LOAD_DATA'; export const UPDATE_DATA = 'UPDATE_DATA'; // Create the actions export const loadData = () => { return { type: LOAD_DATA, payload: 'Data', }; }; // Create the reducer const initialState = {}; const rootReducer = combineReducers({ app: (state = initialState, action) => { switch (action.type) { case LOAD_DATA: return { ...state, data: action.payload }; default: return state; } }, }); // Create the store const store = createStore(rootReducer, applyMiddleware()); // Use the store in your component import React from 'react'; import ReactDOM from 'react-dom'; import { Provider } from 'react-redux'; import store from './store'; const App = () => { const dispatch = useDispatch(); React.useEffect(() => { dispatch(loadData()); }, []); return <p>Example Component</p>; }; ReactDOM.render( <Provider store={store}> <App /> </Provider>, document.getElementById('root') ); ``` For more information about Redux, visit [redux.js.org](https://redux.js.org/). ### Vuex for Vue **What is Vuex?** ---------------- Vuex is a state management library for Vue.js applications. It provides a single source of truth for your application's state and enables predictable and debuggable behavior. **Key Concepts** * **Store**: The central location that holds the entire state of your application. * **Actions**: Payloads that trigger state changes. * **Mutations**: Pure functions that handle actions and update the state. * **Getters**: Functions that select a portion of the state and return it. **Example Usage** ```javascript import Vue from 'vue'; import Vuex from 'vuex'; Vue.use(Vuex); // Define the actions const actions = { load_data({ commit }, data) { commit('UPDATE_DATA', data); }, }; // Define the mutations const mutations = { UPDATE_DATA(state, data) { state.data = data; }, }; // Create the store const store = new Vuex.Store({ state: { data: '', }, mutations, actions, }); // Use the store in your component export default { computed: { data() { return this.$store.state.data; }, }, methods: { load_data() { this.$store.dispatch('load_data', 'Data'); }, }, }; ``` For more information about Vuex, visit [vuex.vuejs.org](https://vuex.vuejs.org/). ### Conclusion In this topic, we introduced state management libraries for each of the frameworks supported by Ionic. These libraries provide a robust and scalable way to manage global state in your applications. Now that you've learned about NgRx, Redux, and Vuex, practice integrating them into your Ionic applications. If you have any questions or need help, feel free to ask in the comments section below. **What's Next?** In the next topic, "Integrating State Management into Ionic Applications," we'll explore how to integrate NgRx, Redux, or Vuex into your Ionic application. **References** * [ngrx.io](https://ngrx.io/) * [redux.js.org](https://redux.js.org/) * [vuex.vuejs.org](https://vuex.vuejs.org/)