Vue3学习笔记-setup

是什么

组合（composition）API的入口

setup 所处的生命周期

• beforeCreate -> use setup()
• created -> use setup()
• beforeMount -> onBeforeMount
• mounted -> onMounted
• beforeUpdate -> onBeforeUpdate
• updated -> onUpdated
• beforeDestroy -> onBeforeUnmount
• destroyed -> onUnmounted
• errorCaptured -> onErrorCaptured

参数(props,context)

props

父组件传递的props

father

<template>
  <div>
    <child :dataFromFather="name" >
    </child>
  </div>
</template>

<script >
import { ref } from "@vue/runtime-core";
import child from "./child.vue";
export default {
  components: {
    child,
  },
  setup() {
    let name=ref('来自父组件的数据')
    return {name}
  },
};
</script>
>

child

    props:['dataFromFather'],
    setup(props, context) {
    	console.log('dataFromFather=',props.dataFromFather)  
       // 输出的是  '来自父组件的数据'
   }

context

• attrs

• slots

  father

   <child >
        <template v-slot:slot1>
          <h1>使用slot1</h1>
        </template>
  
        <template v-slot:slot2>
          <p>使用slot2</p>
        </template>
    </child>
  

  child

  // 定义slot1 和 slot2
  <template>
    <div>
      <p>slot1</p>
      <slot name="slot1"></slot>
    </div>
    <div>
      <p>slot2</p>
      <slot name="slot2"></slot>
    </div>
  </template>
  
  <script>
  export default {
    setup(props, context) {
      console.log("1=", context.slots);
      onMounted: {
        console.log("2=", context.slots);
      }
    },
  };
  // 这里的打印结果 
  1=和2= 是一致的，打印的都是Proxy：slot1和slot2
  ！！！
  若是father注释slot2的使用，那么只会打印proxy：slot1
  </script>
  

• emit

  child

  <template>
    <div>
      <button @click="show">子组件</button>
    </div>
  </template>
  
  <script>
  export default {
    setup(props, context) {
      function show(){
          context.emit('childShow','来自子组件')
      }
      return {show}
    },
  };
  </script>
  

  father

  <template>
    <div>
      <child @childShow='fatherShow'>
      </child>
    </div>
  </template>
  
  <script lang='ts'>
  import { onMounted } from "@vue/runtime-core";
  import child from "./child.vue";
  export default {
    components: {
      child,
    },
    setup(props, context) {
      function fatherShow(data:any){
        console.log(data)
      // 这里输出的是 ‘来自子组件
      }
      return {fatherShow}
    },
  };
  </script>
  
  

使用渲染函数

import { h, ref, reactive } from 'vue'
export default {
  setup() {
    const readersNumber = ref(0)
    const book = reactive({ title: 'Vue 3 Guide' })
    // 请注意，我们需要在这里显式地暴露ref值
    return () => h('div', [readersNumber.value, book.title])
  }
}