Vue3 自定义指令

// 完整写法
const 指令名 = {
  mounted: (el, binding) => {},
  updated: (el, binding) => {}
}
 
// 简写
const 指令名 = (el, binding) => {}
 
// 选项式写法
export default {
  ......
  directives: {
    // 完整写法
    big: {
      mounted: (el, binding) => {},
      updated: (el, binding) => {}
    },
    // 简写
    bigs(el, binding) {}
  }
}

<template>
  <p>当前的num值是：<span v-text="num"></span></p>
  <p>放大10倍的num值是：<span v-big="num"></span></p>
  <button @click="num++">点击num+1</button>
</template>
 
<script setup>
import { ref } from "vue";
let num = ref(1);
// 创建自定义指令
const vBig = {
  // 绑定的元素挂载时执行
  mounted: (el, binding) => {
    console.log(el); // 绑定指令的 DOM 元素
    console.log(binding); // 绑定指令的对象
    el.innerText = binding.value * 10;
  },
  // 绑定的值更新时执行
  updated: (el, binding) => {
    console.log(el); // 绑定指令的 DOM 元素
    console.log(binding); // 绑定指令的对象
    el.innerText = binding.value * 10;
  }
}
</script>

<template>
  <p>当前的num值是：<span v-text="num"></span></p>
  <p>放大10倍的num值是：<span v-big="num"></span></p>
  <button @click="num++">点击num+1</button>
</template>
 
<script setup>
import { ref } from "vue";
let num = ref(1);
// 简写：在 mounted 和 updated 时执行
const vBig = (el, binding) => {
  console.log(el); // 绑定指令的 DOM 元素
  console.log(binding); // 绑定指令的对象
  el.innerText = binding.value * 10;
}
</script>