vue3自定义指令自动获取节点的width和height代码示例

"vue": "^3.4.29"

class ResizeObserverStore {
    // 存储目标元素和对应的ResizeObserver实例
    observer= new Map<HTMLElement, ResizeObserver[]>();
    // 获取目标元素对应的ResizeObserver实例
    get(target: HTMLElement) {
        return this.observer.get(target) || [];
    }
    // 设置目标元素对应的ResizeObserver实例
    set(target: HTMLElement, observer: ResizeObserver) {
        const observers = this.observer.get(target);
        if (observers) {
            observers.push(observer);
        } else {
            this.observer.set(target, [observer]);
        }
    };
    // 销毁目标元素对应的ResizeObserver实例
    remove(target: HTMLElement) {
        const observers = this.observer.get(target);
        // 销毁事件
        if (observers) {
            observers.forEach(observer => {
                observer.disconnect();
            });
            this.observer.delete(target);
        }
    }
}
// 创建一个ResizeObserverStore实例
const resizeObserverStore = new ResizeObserverStore();

//  使用ResizeObserver监听目标元素的变化
export const useResizeObserver = (target: HTMLElement, callback: ResizeObserverCallback) => {
    const observer = new ResizeObserver(callback);
    observer.observe(target);
    resizeObserverStore.set(target, observer);
    return observer;
}

// 移除ResizeObserver监听
export const removeResizeObserver = (target: HTMLElement) => {
    resizeObserverStore.remove(target);
}

import {App, Directive} from "vue";
import {removeResizeObserver, useResizeObserver} from "ResizeObserverStore.ts";


export const  vSize: Directive = {
    mounted: (el, binding) => {
        // 注册并使用resizeObserver
        useResizeObserver(el, (entries) => {
            binding.value.width = entries[0].contentRect.width
            binding.value.height = entries[0].contentRect.height
        })
    },
    beforeUnmount: (el) => {
        // 销毁resizeObserver
        removeResizeObserver(el)
    },
}

export default (app: App)=>{
    app.directive('size', vSize)
}

import {createApp} from "vue";
import App from "./App.vue";
import directives from "../directives";

const app = createApp(App)
// 在这里注册以下就可以使用了
directives(app)
app.mount("#app");

<template>
  <div class="layout-box" v-size="size"></div>
</template>

<script setup lang="ts">
  import {reactive, ref, watch, watchEffect} from "vue";
  // 如果全局引入的话就不用在这里引用了
  import {vSize} from "../directives";
  const size = reactive({
    width: 0,
    height: 0
  })
  watchEffect(
      () => {
        console.log(size.width, size.height)
      }
  )
</script>

<style lang="scss" scoped>
.layout-box{
  width: 100px;
  height: 100px;
  background-color: #f5f5f5;
  border: 1px  solid #bd34fe;
  overflow: auto;
  resize: both;
}
</style>