How to use setup and custom instructions in Vue3

setup syntactic sugar

The biggest advantage is that all declaration parts can be used directly without return.

Note: Some functions are not yet complete, such as: name and render need to be added separately. Tags are written according to the compositionAPI method

// You can also add <script></script>

setup syntactic sugar unique

<script setup>
import { ref ,reactive,toRefs } from &#39;vue&#39;
const a = 1;
const num = ref(99)  // 基本数据类型
const user = reactive({ // 引用数据类型
  age:11
})
// 解构能获取响应式属性 {}解构 toRefs保留响应式
const { age } = toRefs(user)
// 导出
defineExpose({
  a
})
// props
const props = defineProps({
  foo: String
})
// 事件
const emit = defineEmits([&#39;change&#39;, &#39;delete&#39;])
// 自定义指令
const vMyDirective = {
  created(el, binding, vnode, prevVnode) {
    // 下面会介绍各个参数的细节
    console.log(&#39;创建了&#39;)
  },
}
</script>

defineProps under setup defineEmits is related to the component application

// 子组件
<template>
  <div class="hello">
    <h2>{{ msg }}</h2>
    <slot name="btn">
 
    </slot>
    <button @click="chickMe"></button>
  </div>
</template>
 
<script setup>
import { useSlots, useAttrs } from &#39;vue&#39;;
 
const slots = useSlots()
const attrs = useAttrs()
const props = defineProps({
  msg: String
})
const emit = defineEmits([&#39;change&#39;])
console.log(slots, attrs)
const chickMe = ()=>{
  emit(&#39;change&#39;,&#39;abc&#39;)
}
 
</script>
 
// 父组件
<template>
  <div class="home" >
    <HelloWorld msg="hello" atr="attrs" @change="changeP ">
      <template #btn>
        <div>我是 btn：{{ obj.text }}</div>
      </template>
    </HelloWorld>
  </div>
</template>
 <script setup>
import HelloWorld from &#39;../components/HelloWorld.vue&#39;;
import { ref ,reactive,toRefs } from &#39;vue&#39;
 const obj = reactive({
      id: 0,
      text: &#39;小红&#39;
    })
 const changeP=(e)=>{
      console.log(e)
    }
</script> 
、

defineExpose is related to the component application

// 子组件
<template>
  <div class="hello">
        123
  </div>
</template>
 
<script setup>
 
const testPose =()=>{
  console.log(&#39;子组件暴露方法&#39;)
}
defineExpose({
  testPose
})
</script>
 
// 父组件
<template>
  <div class="home" v-test>
    <HelloWorld  ref="helloSon"></HelloWorld>
    <button @click="testEpose"></button>
  </div>
</template>
<script setup>
import HelloWorld from &#39;../components/HelloWorld.vue&#39;;
import { ref } from &#39;vue&#39;
// setup函数的话可以从context上查找
const helloSon = ref(null);
const testEpose = () => {
  helloSon.value.testPose();
}
</script>

custom directive

• created: in Called before the bound element's attribute or event listener is applied. This is useful when a directive needs to be appended to an event listener before the normal v-on event listener is called.

• beforeMount: Called when the directive is bound to the element for the first time and before the parent component is mounted.

• mounted: Called after the parent component of the bound element is mounted. Most of the custom instructions are written here.

• beforeUpdate: Called before updating the VNode containing the component.

• updated: Called after the containing component’s VNode and the VNodes of its subcomponents are updated.

• beforeUnmount: Called before unmounting the parent component of the bound element

• unmounted: When the directive is unbound from the element and the parent component has been unmounted , it is only called once.

import { createApp } from 'vue';
const Test = createApp();
Test.directive('my-directive', {
    // 在绑定元素的 attribute 前
    // 或事件监听器应用前调用
    created(el, binding, vnode, prevVnode) {
        // 下面会介绍各个参数的细节
        console.log('创建了')
    },
    // 在元素被插入到 DOM 前调用
    beforeMount(el, binding, vnode, prevVnode) { },
    // 在绑定元素的父组件
    // 及他自己的所有子节点都挂载完成后调用
    mounted(el, binding, vnode, prevVnode) { },
    // 绑定元素的父组件更新前调用
    beforeUpdate(el, binding, vnode, prevVnode) { },
    // 在绑定元素的父组件
    // 及他自己的所有子节点都更新后调用
    updated(el, binding, vnode, prevVnode) { },
    // 绑定元素的父组件卸载前调用
    beforeUnmount(el, binding, vnode, prevVnode) { },
    // 绑定元素的父组件卸载后调用
    unmounted(el, binding, vnode, prevVnode) { }
})
 
export default Test.directive('my-directive');

• el: The element to which the directive is bound. This can be used to directly manipulate the DOM.

• binding: An object containing the following properties.

• value: The value passed to the directive. For example, in v-my-directive="1 1", the value is 2.

• oldValue: The previous value, only available in beforeUpdate and updated. It is available whether the value changes or not.

• arg: The arguments passed to the directive (if any). For example, in v-my-directive:foo, the parameter is "foo".

• modifiers: An object containing modifiers (if any). For example, in v-my-directive.foo.bar, the modifier object is { foo: true, bar: true }.

• instance: The component instance using this directive. dir: The definition object of the instruction.

• vnode: Represents the underlying VNode of the bound element.

• prevNode: The VNode representing the element to which the directive is bound in the previous rendering. Only available in beforeUpdate and updated hooks.

Application

<template>
  <div class="home" v-test>
  </div>
</template>
//setup 外部调用
<script>
// 指令必须 vXxx 这样书写
import vTest from &#39;./TestDirective&#39;
export default defineComponent({
   directives: {
      test:vTest,
    },
  setup(props) {
    // console.log(&#39;Test&#39;,vTest)
    
    return {
   
    };
  } 
})
</script>
//或者 setup内部
<script setup>
import vTest from &#39;./TestDirective&#39;
</script>

Object literal

<div v-demo="{ color: &#39;white&#39;, text: &#39;hello!&#39; }"></div>
 
app.directive(&#39;demo&#39;, (el, binding) => {
  console.log(binding.value.color) // => "white"
  console.log(binding.value.text) // => "hello!"
})

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