示例

使用emits选项来声明从组件发出哪些自定义事件。

export default {
  emits: ['custom-event'],
  methods: {
    notifyParent() {
      this.$emit('custom-event','Hello! ')
    }
  }
}

示例

使用 props 作为带有选项的对象，以便在父组件未提供时显示默认的食物描述。

FoodItem.vue:

<template>
	<div>
		<h2>{{ foodName }}</h2>
		<p>{{ foodDesc }}</p>
	</div>
</template>

<script>
export default {
	props: {
		foodName: {
			type: String,
			required: true
		},
		foodDesc: {
			type: String,
			required: false,
			default: 'This is the food description...'
		}
	}
};
</script>

App.vue:

<template>
  <h1>Food</h1>
  <p>Food description is not provided for 'Pizza' and 'Rice', so the default description is used.</p>
  <div id="wrapper">
    <food-item 
      food-name="Apples" 
      food-desc="Apples are a type of fruit that grow on trees."/>
    <food-item 
      food-name="Pizza"/>
    <food-item 
      food-name="Rice"/>
  </div> 
</template>

<style>
  #wrapper {
    display: flex;
    flex-wrap: wrap;
  }
  #wrapper > div {
    border: dashed black 1px;
    flex-basis: 120px;
    margin: 10px;
    padding: 10px;
    background-color: lightgreen;
  }
</style>