Vuex

The way data is shared between components

The parent passes values to the child using the property bind v-bind
The child passes the value V-on to the parent using the event binding
Sharing data between sibling components: EventBus
- $on The component that receives the data
- Which component $emit sends data to

What is Vuex

Vuex is a state management mode developed specifically for vue.js applications. It uses centralized storage to manage the status of all components of applications, which makes it more convenient to realize data sharing among components.

Advantages of using Vuex to manage data

Centralized management of shared data in Vue facilitates development and maintenance
It can realize data sharing among components and improve development efficiency
The data stored in Vuex is responsive, and whenever the data is changed, the data in the page is updated synchronously.

Scenarios using Vuex

In general, only data that is shared between arrays is necessarily stored in Vuex
A component’s private data is stored in its own component’s data

Basic use of Vuex

Installation Scheme 1

NPM installs Vuex dependency packages
```
npm install vauex --save 
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```

Import Vuex package

Import Vuex from "Vuex" vue. use(Vuex) // Mount to VueCopy the code

Creating a Store object

const store=new Vuex.Store({
  //state stores globally shared dataState: {count:0}})Copy the code

4. Mount the Store object to the Vue instance

new Vue({
 el:"#app".render:h= >(app),
 router,
 // All components can get global data directly from store
 store
})
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Installation Scheme 2

Open the terminal and enter the command vue UI
Create the project and set the project name and package manager
Set the manual configuration item
Setting function Items
Standard configuration, create projects.

Core features in Vuex

State (data)

Component to access data in StateMethods a

State provides the only common data source where all shared data is stored

// Create a store data source that provides unique public data
const store= newVuex. Store ({state: {count:0}})Copy the code

// The first way to access data in State in an interpolation expression in a component
this$store.state. Global data nameCopy the code

Component to access data in StateWay 2

// Import mapState functions from vuEX as needed
import {mapState} from 'vuex'

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// Map global data needed by the current component to computed properties of the current component using the mapState function you just imported
  computed: {... mapState(['count']) // Use the extension operator... MapState can be mapped to computed properties of the current component
  }
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Mutation (method)

Mutation cannot execute asynchronous tasks. Asynchronous tasks need Action

Mutation is used to change data in the Store`(the way a`)

Store data can only be changed by Mutation, but data in Store cannot be manipulated directly
This is a slightly more cumbersome way to operate, but you can monitor all data changes centrally
Use this. Codestore.mit in the component’s methods to get the mutation methods
Parameters can be passed when mutation is triggered

<script>
   // Mutation is defined in the store. vue file
 const store=new Vuex.Store({
   state: {count:0
   },
   mutations: {// Change data only, no parameter is passed
     add(state){
      // Change the stateThe state count++},// The step parameter is passed when mutation is triggered
     addN(state,step){
      // Change the data
      state.count+=step
    } 
   }
 })
 <script>

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 <script>
// Use trigger Mutation in the component
  methods:{
    handle1(){
   //commit is used to trigger a function of mutation
    this.$store.commit("add")}handle2(){
     //commit is used to trigger the mutation function and carry parameters
     this.$store.commit("addN".3)
    }
  }
<script>
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Trigger mutation`Way 2`

Import the mapMutations function from Vuex on demand

// Import the mapMutations function from VUEX on demand
 import {mapMutations} from "vuex"
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Through the newly imported mapMutations function, the required mutations function is mapped to the methods of the current component

The use of… Extension operators can also pass arguments

<script>
// Map the mutations function to the methods function of the current componentMethods: {... mapMutations(["add"."addN"])  //add, and addN is the mutation method
   handle1(){
     this.add() // Use the add method of mutation},handle2(){
    this.addN(3) // use the addN method of mutation and pass parameter 3
   }
}
<script>
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Action (Performing asynchronous tasks)

Action is used to process asynchronous tasks

Trigger the Action asynchronous taskMethods a
- To manipulate asynchronously changed data, you must use the Action, not Mutation, but must do so in the ActionChange data indirectly by triggering Mutation
- Used in componentsThis.$store.dispatch(" method name ")Trigger Action

<script>
// In the store.vue file
const store=new Vuex.store({
   state: {count:0
   },
  mutations: {add(state){
      state.count++
    },
    addN(state){
      state.count++
    }
  },
  actions: {// Actions handles asynchronous operations
    addAsync(context){
     setTimeout(() = >{
       context.commit("add") //commit triggers the add method of mutation
      },1000)},addNAsync(context,step){
      setTimeout(() = >{
        context.commit("addN",step)//commit triggers the mutation addN and carries the step parameter
      },1000)
    }
  }
})
<script>
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<script>
// Use trigger actions in the component
methods:{
  handle1(){
    // The first way to trigger actions
     this.$store.dispatch("addAsync")},handle2(){
     // Dispatch triggers asynchrony of actions and carries parameters
      this.$store.dispatch("addNAsync".5)
   }
 }
<script>
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Trigger Action Asynchronous task mode 2

. MapActions (” method name “) is the second way to trigger actions

// Import mapActions functions from vuex as needed
 import mapActions from "vuex"
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Map the required Actions functions to the current component’s methods using the newly imported mapActions function

<script>
// Map the actions function to the methodes function of the current componentmethods{ ... mapActions(["add"."addN"])
   handle1(){
     this.add() // Use the add method of mutation},handle2(){
    this.addN(3) // use the addN method of mutation and pass parameter 3
   }
}
<script>
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Getter (process forming new data)

Getters are used to process the data in the Store to form new data, similar to the calculation properties of Vue

The data in the Store changes, the data in the Getter changes

<script>
// Define the Getter in the store file
 const store= newVuex. Store ({state: {count:0
    },
    getters: {// Defines the showNum function
     showNum:state= >{
        return:"The current latest data is' +state.count+ '"
      } 
    }
 })
<script> 
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The first way to use getters in a component is:

this.$store.getters. Function nameCopy the code

The second way to use getters. Map…

Note that it needs to be used in computed properties

import {mapGetters} from "Vuex"
computed: {... mapGetters({"showNum"})}Copy the code

Module (split into modules)

Application scenario: Store,mutation, Action,getter when the project becomes very complex. You can get quite bloated. Modules are split into modules for easy management

Global definitions

ModuleA and moduleB modules are globally defined and finally registered in modules
const moduleA = {
  state: () = >({... }),mutations: {... },actions: {... },getters: {... }}const moduleB = {
  state: () = >({... }),mutations: {... },actions: {... }}const store = createStore({
  modules: {
    a: moduleA,
    b: moduleB
  }
})

store.state.a // -> moduleA status
store.state.b // -> moduleB status
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The module name

Be careful not to conflict by defining two identical getters in different, namespaceless modules

Adding namespaced: True makes it a named module, which makes it more reusable and encapsulation

When a module is registered, all its getters, actions, and mutations are automatically named according to the path the module was registered with. For example: the commit (‘ account/login)

const store = createStore({
  modules: {
/ / parent module
    account: {
      namespaced: true.// Module assets
      state: () = >({... }),// Module states are already nested, and using the 'namespaced' attribute doesn't affect them
      getters: {
        isAdmin () { ... } // -> getters['account/isAdmin']
      },
      actions: {
        login () { ... } // -> dispatch('account/login')
      },
      mutations: {
        login () { ... } // -> commit('account/login')
      },

      // Nested modules
      modules: {
        // Inherits the parent module's namespace
        myPage: {
          state: () = >({... }),getters: {
            profile () { ... } // -> getters['account/profile']}},// Further nested namespaces
        posts: {
          namespaced: true.state: () = >({... }),getters: {
            popular () { ... } // -> getters['account/posts/popular']}}}}}})Copy the code

Adjustments to access data and modify data

To access data in a module, add the module name

Get the data item: {{$store.state. Module name. Getters: {{$store. Getters [$store.'Module name /getters name']}}
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Access mutations/ Actions in the module:
- If namespaced is true, you need to add an additional module name
- If namespaced is false, no additional module name is required
```
$store.commit('mutations name')        / / namespaced to false
$store.commit('Module name /mutations name')  / / namespaced to true
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```

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The way data is shared between components

What is Vuex

Advantages of using Vuex to manage data

Scenarios using Vuex

Basic use of Vuex

Core features in Vuex

State (data)

Component to access data in State`Methods a`

Component to access data in State`Way 2`

Mutation (method)

Mutation is used to change data in the Store`(the way a`)

Trigger mutation`Way 2`

Action (Performing asynchronous tasks)

Getter (process forming new data)

Module (split into modules)

“Likes, favorites and comments”

Vuex

The way data is shared between components

What is Vuex

Advantages of using Vuex to manage data

Scenarios using Vuex

Basic use of Vuex

Core features in Vuex

State (data)

Component to access data in StateMethods a

Component to access data in StateWay 2

Mutation (method)

Mutation is used to change data in the Store(the way a)

Trigger mutationWay 2

Action (Performing asynchronous tasks)

Getter (process forming new data)

Module (split into modules)

“Likes, favorites and comments”

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Component to access data in State`Methods a`

Component to access data in State`Way 2`

Mutation is used to change data in the Store`(the way a`)

Trigger mutation`Way 2`