详细分析Vue3中的emit用法(子传父)
目录
- 1. 基本知识
- 1.1 emit
- 1.2 defineEmits
- 2. Demo
1. 基本知识
在 Vue 3 中,emit 是一种机制,用于在子组件中触发事件,并在父组件中监听这些事件
提供一种组件间通信的方式,尤其是在处理父子组件数据传递和交互时非常有用
一共有两种方式
1.1 emit
子组件中使用emit
<template><button @click="handleClick">Click me</button>
</template><script>
export default {name: 'ChildComponent',methods: {handleClick() {this.$emit('custom-event', 'Hello from child');}}
}
</script>
父组件监听子组件:
<template><div><ChildComponent @custom-event="handleCustomEvent" /></div>
</template><script>
import ChildComponent from './ChildComponent.vue';export default {name: 'ParentComponent',components: {ChildComponent},methods: {handleCustomEvent(payload) {console.log(payload); // 输出 'Hello from child'}}
}
</script>
1.2 defineEmits
在 Vue 3 中,还可以使用 Composition API 的 defineEmits 方法来定义和使用 emit
子组件中定义和使用emit:
<template><button @click="emitEvent">Click me</button>
</template><script setup>
import { defineEmits } from 'vue';const emit = defineEmits(['custom-event']);function emitEvent() {emit('custom-event', 'Hello from child with Composition API');
}
</script>
父组件监听子组件:
<template><div><ChildComponent @custom-event="handleCustomEvent" /></div>
</template><script>
import ChildComponent from './ChildComponent.vue';export default {name: 'ParentComponent',components: {ChildComponent},methods: {handleCustomEvent(payload) {console.log(payload); // 输出 'Hello from child with Composition API'}}
}
</script>
2. Demo
完整Demo如下:
- 创建子组件:
<template><button @click="emitEvent">Click me</button>
</template><script setup>
import { defineEmits } from 'vue';const emit = defineEmits(['custom-event']);function emitEvent() {emit('custom-event', 'Hello from child with Composition API');
}
</script>
- 创建父组件:
<template><div><ChildComponent @custom-event="handleCustomEvent" /><p>{{ message }}</p></div>
</template><script>
import ChildComponent from './ChildComponent.vue';
import { ref } from 'vue';export default {name: 'ParentComponent',components: {ChildComponent},setup() {const message = ref('');function handleCustomEvent(payload) {message.value = payload;}return {message,handleCustomEvent};}
}
</script>
- 应用组件:
<template><ParentComponent />
</template><script>
import ParentComponent from './components/ParentComponent.vue';export default {name: 'App',components: {ParentComponent}
}
</script>
主入口文件:
import { createApp } from 'vue';
import App from './App.vue';createApp(App).mount('#app');