vue3.x中emits的基本用法实例

<template>
  <teleport to="#modal">
    <div id="center" v-if="isOpen">
      <h2>
        <slot>this is a modal</slot>
      </h2>
      <button @click="clickButton">close</button>
    </div>
  </teleport>
</template>
<script lang="ts">
import { defineComponent } from 'vue';

export default defineComponent({
  props: {
    isOpen: Boolean,
  },
  emits: {
    'close-modal': null,
  },
  setup(props, context) {
    const clickButton = () => {
      context.emit('close-modal');
    };
    return {
      clickButton,
    };
  },
});
</script>

<style scoped>
#center {
  width: 200px;
  height: 200px;
  border: 2px solid black;
  background: white;
  position: fixed;
  left: 50%;
  top: 50%;
  margin-left: -100px;
  margin-top: -100px;
}
</style>

<template>
  <div id="main">
    <modal :isOpen="modalIsOpen" @close-modal="onModalClose">my modal</modal>
    <button @click="onModalOpen">Open Modal</button>
  </div>
</template>

<script lang="ts">
import { defineComponent, ref } from 'vue';
import Modal from './components/Modal.vue';

export default defineComponent({
  components: { Modal },
  name: 'App',
  setup(){
    const modalIsOpen = ref(false)
    const onModalOpen = ()=>{
      modalIsOpen.value = true
    }
    const onModalClose = ()=>{
      modalIsOpen.value = false
    }
    return{
      onModalOpen,
      onModalClose,
      modalIsOpen
    }
  }
});
</script>

<style>
#app {
  font-family: Avenir, Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-align: center;
  color: #2c3e50;
  margin-top: 60px;
}
button {
  font-size: 2rem;
}
</style>

<template>
  <!-- teleport的使用  to属性渲染到id为 teleport-test 的元素身上   在index.html中-->
  
   <div id="center" v-if="isOpen">
     <slot>插槽</slot>
     <button @click="buttonClick">关闭模态框</button>
   </div>
</template>
<script lang="ts">
import { defineComponent } from "vue";
export default defineComponent({
  props:{

    isOpen: {
      type: Boolean,
      required: true
    },
  },
  // emits 写自定义事件  作用 比较清晰知道该组件有那些自定义事件
  emits: {
    // 无需验证写法
    'close-model': null,

    // 这种写法  自定义函数  可以在运行时验证参数是否正确
    'close-modals': (payload: any) => {
      return payload.type === 'close'
    }
  },
  setup(props,context) {
    const buttonClick = () => {
      context.emit('close-model')
    }

    // 这种写法来校验
    context.emit('close-modals',{
      // 如果验证失败会有一个警告
      type: 'close'
      // type: 'sss'
    })
    return {
      buttonClick
    }
  }
})

</script>

<style>
#center{
  width: 600px;
  height: 300px;
  border: 1px solid #999;
  background-color: #fff;
  position: fixed;
  left: 50%;
  top: 50%;
  margin-left: -300px;
  margin-top: -150px;
}
</style>