How to use setup, ref and reactive in vue3

1. First introduction to the use of setUp

Briefly introduce the function of the following code:
Use the ref function to monitor changes in a certain variable and render it to the view.
The setUp function is the entry function of the combination API. This is very important.
setUp can monitor changes in variables! We will make use of it
ref is built in vue and needs to be imported.

<template>
 <div>{{ countNum}}</div>
 <button @click="handerFunc">按钮</button>
</template>
<script>
import {ref} from 'vue'
export default {
  name: 'App',
  setup() {
    // 这一句表示的是定义了一个变量count。这个变量的初始值是100
    let countNum=ref(100);

    // 在组合API中，如果想定义一个方法，不用定义到methods中去。直接定义就可以了
    function handerFunc(){
      // console.log(countNum);//countNum是一个对象
      countNum.value += 10;
    }
    //在组合api中定义的方法，或者变量。如果外界需要使用，那么必须通过 return  {aaa,func} 的方式暴露出去
    return { countNum ,handerFunc}
  }
}
</script>

2 Understand the use of reactive

The ref function can only monitor simple types of data changes.
Cannot monitor changes in complex types (arrays, objects).
So our protagonist reactive appears.
The function in setup will be executed automatically once.

<template>
 <div>
   <ul>
     <li v-for="item in satte.arr" :key="item.id">
       {{item.name  }}
     </li>
   </ul>

 </div>
</template>
<script>
import {reactive} from 'vue'
export default {
  name: 'App',
  setup(){
    console.log("setUp会自动执行的")
    // ref函数的注意点：
    // ref函数只能够去监听简单类型的数据变化，不能够去监听，复杂类型的变化(数组、对象)
    // reactive  方法里面是一个对象
    let satte=reactive({
       arr:[
         {name:"司藤",id:'0011'},
         {name:"皮囊之下",id:'0011'},
         {name:"百岁之约",id:'0012'},
         {name:"三生三世",id:'0013'},
       ]
    })
    return { satte }
  },
}
</script>

3 Use reactive

to implement view deletion

<template>
 <div>
   <ul>
     <li v-for="(item,index) in satte.arr" :key="index" @click="del(index)">
       {{item.name  }}
     </li>
   </ul>

 </div>
</template>
<script>
import {reactive} from 'vue'
export default {
  name: 'App',
  setup(){
    let satte=reactive({
       arr:[
         {name:"司藤",id:'0011'},
         {name:"皮囊之下",id:'0011'},
         {name:"百岁之约",id:'0012'},
         {name:"三生三世",id:'0013'},
       ]
    })
    // 删除被点击的元素
    function del(index){
      for(let i=0;i<satte.arr.length;i++){
        if(index==i){
          satte.arr.splice(i,1)
        }
      }
    }
    return { satte, del}
  },
}
</script>

4 Separate the deletion logic

Form a separate module

<template>
 <div>
   <ul>
     <li v-for="(item,index) in satte.arr" :key="index" @click="del(index)">
       {{item.name  }}
     </li>
   </ul>

 </div>
</template>
<script>
import {reactive} from 'vue'
export default {
  name: 'App',
  setup(){
    // onlyDelLuoJi() 方法中含有一个数组 和一个方法；类似于解构
    let {satte,del }=onlyDelLuoJi();
    
    // 暴露给外界使用
    return { satte,del}
  },
}

function onlyDelLuoJi(){
   let satte=reactive({
       arr:[
         {name:"司藤",id:'0011'},
         {name:"皮囊之下",id:'0011'},
         {name:"百岁之约",id:'0012'},
         {name:"三生三世",id:'0013'},
       ]
    })
    // 删除被点击的元素
    function del(index){
      for(let i=0;i<satte.arr.length;i++){
        if(index==i){
          satte.arr.splice(i,1)
        }
      }
    }
    // 将数据satte 和方法 del 暴露出去
    return { satte,del }
}
</script>

5. Implement the add function

Pass parameters between events

<template>
 <div>
   <div>
      <input type="text" v-model="addobj.watchTv.name">
      <button @click="addHander">添加</button>
   </div>
   
   <ul>
     <li v-for="(item,index) in satte.arr" :key="index" @click="del(index)">
       {{item.name  }}
     </li>
   </ul>

 </div>
</template>
<script>
import {reactive} from 'vue'
export default {
  name: 'App',
  setup(){
    // onlyDelLuoJi() 方法中含有一个数组 和一个方法；类似于解构
    let {satte,del }=onlyDelLuoJi();
    
    // 传递参数satte 是onlyDelLuoJi函数中提供的satte。进行传递
    let {  addobj,addHander  }=OnlyaddHander(satte);

    // 暴露给外界使用
    return { satte,del,addobj, addHander}
  },
}

//添加功能模块
function OnlyaddHander(satte){
  console.log('初始化添加',satte)
    let addobj=reactive({
        watchTv:{
          name:"",
          id:""
        }
     });

    function addHander(){
      // 重置清空 错吴做法
        // satte.arr.push(addobj.watchTv)
        // addobj.watchTv.name = ""; 
        // addobj.watchTv.id = "";
        

          // 正确做法
        let oldobj = Object.assign({}, addobj.watchTv)
        satte.arr.push(oldobj)
    }
    return { addobj,addHander }
}

//删除功能模块
function onlyDelLuoJi(){
  console.log('删除初始化')
   let satte=reactive({
       arr:[
         {name:"司藤",id:'0011'},
         {name:"皮囊之下",id:'0011'},
         {name:"百岁之约",id:'0012'},
         {name:"三生三世",id:'0013'},
       ]
    })
    // 删除被点击的元素
    function del(index){
      for(let i=0;i<satte.arr.length;i++){
        if(index==i){
          satte.arr.splice(i,1)
        }
      }
    }
    // 将数据satte 和方法 del 暴露出去
    return { satte,del }
}
</script>

6 Extract them into separate files

We want to add and delete related logic , extracted into a separate file.
add.js is the relevant logic for adding
del.js is the relevant logic for deletion

import { reactive } from "vue"
function OnlyaddHander(satte){
  console.log('初始化添加',satte)
    let addobj=reactive({
        watchTv:{
          name:"",
          id:""
        }
     });
    function addHander(e){
        // 重置清空 错吴做法
        // satte.arr.push(addobj.watchTv)
        // addobj.watchTv.name = ""; 
        // addobj.watchTv.id = "";
        // 正确做法
        let oldobj = Object.assign({}, addobj.watchTv)
        satte.arr.push(oldobj)
        e.preventDefault();
    }
    return { addobj,addHander }
}
export default  OnlyaddHander

adel.js

import {reactive } from "vue"
function onlyDelLuoJi() {
  console.log('删除初始化')
   let satte=reactive({
       arr:[
         {name:"司藤",id:'0011'},
         {name:"皮囊之下",id:'0011'},
         {name:"百岁之约",id:'0012'},
         {name:"三生三世",id:'0013'},
       ]
    })
    // 删除被点击的元素
    function del(index){
      for(let i=0;i<satte.arr.length;i++){
        if(index==i){
          satte.arr.splice(i,1)
        }
      }
    }
    // 将数据satte 和方法 del 暴露出去
    return { satte,del }
}
export default  onlyDelLuoJi

Main file

<template>
 <div>
   <div>
      <input type="text" v-model="addobj.watchTv.name">
      <button @click="addHander">添加</button>
   </div>
   
   <ul>
     <li v-for="(item,index) in satte.arr" :key="index" @click="del(index)">
       {{item.name  }}
     </li>
   </ul>

 </div>
</template>
<script>
import onlyDelLuoJi from "./components/del"
import OnlyaddHander from "./components/add"
export default {
  name: 'App',
  setup(){
    // onlyDelLuoJi() 方法中含有一个数组 和一个方法；类似于解构
    let {satte,del }=onlyDelLuoJi();
    
    // 传递参数
    let {  addobj,addHander  }=OnlyaddHander(satte);

    // 暴露给外界使用
    return { satte,del,addobj, addHander}
  },
}
</script>

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