vue+Elementui，实现弹窗在可视范围内进行拖拽

import Vue from "vue";

// v-dialogDrag: 弹窗拖拽
Vue.directive("dialogDrag", {
  bind(el, binding, vnode) {
    //拿到拖拽元素及弹窗元素
    const dialogHeaderEl = el.querySelector('.el-dialog__header')
    const dragDom = el.querySelector('.el-dialog')
    dialogHeaderEl.style.cssText += ';cursor:move;'
    dragDom.style.cssText += ';top:0px;'

    //给弹窗加上overflow auto；不然缩小时框内的标签可能超出dialog；
    dragDom.style.overflow = "hidden";
    dragDom.style.userSelect = 'auto';

     //清除选择头部文字效果

    dialogHeaderEl.onselectstart = new Function("return false");

    // 获取原有属性 ie dom元素.currentStyle 火狐谷歌 window.getComputedStyle(dom元素, null);
    const getStyle = (function() {
      if (window.document.currentStyle) {
        return (dom, attr) => dom.currentStyle[attr]
      } else {
        return (dom, attr) => getComputedStyle(dom, false)[attr]
      }
    })()

    dialogHeaderEl.onmousedown = (e) => {
      // 鼠标按下，计算当前元素距离可视区的距离
      const disX = e.clientX - dialogHeaderEl.offsetLeft
      const disY = e.clientY - dialogHeaderEl.offsetTop

      const dragDomWidth = dragDom.offsetWidth
      const dragDomHeight = dragDom.offsetHeight

      const screenWidth = document.body.clientWidth
      const screenHeight = document.body.clientHeight

      const minDragDomLeft = dragDom.offsetLeft
      const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth

      const minDragDomTop = dragDom.offsetTop
      const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomHeight

      // 获取到的值带px 正则匹配替换
      let styL = getStyle(dragDom, 'left')
      let styT = getStyle(dragDom, 'top')

      if (styL.includes('%')) {
        styL = +document.body.clientWidth * (+styL.replace(/\%/g, '') / 100)
        styT = +document.body.clientHeight * (+styT.replace(/\%/g, '') / 100)
      } else {
        styL = +styL.replace(/\px/g, '')
        styT = +styT.replace(/\px/g, '')
      }

      document.onmousemove = function(e) {
        // 通过事件委托，计算移动的距离
        let left = e.clientX - disX
        let top = e.clientY - disY

        // 边界处理
        if (-(left) > minDragDomLeft) {
          left = -minDragDomLeft
        } else if (left > maxDragDomLeft) {
          left = maxDragDomLeft
        }

        if (-(top) > minDragDomTop) {
          top = -minDragDomTop
        } else if (top > maxDragDomTop) {
          top = maxDragDomTop
        }

        // 移动当前元素
        dragDom.style.cssText += `;left:${left + styL}px;top:${top + styT}px;`

        // emit onDrag event
        vnode.child.$emit('dragDialog')
      }

      document.onmouseup = function(e) {
        document.onmousemove = null
        document.onmouseup = null
      }
    }
  }
});
Vue.directive("commonDrag", {
  //1.指令绑定到元素上回立刻执行bind函数，只执行一次
  //2.每个函数中第一个参数永远是el，表示绑定指令的元素，el参数是原生js对象
  //3.通过el.focus()是无法获取焦点的，因为只有插入DOM后才生效
  bind: function () {},
  //inserted表示一个元素，插入到DOM中会执行inserted函数，只触发一次
  inserted: function (el) {
    el.onmousedown = function (e) {
      var disx = e.pageX - el.offsetLeft;
      var disy = e.pageY - el.offsetTop;
      document.onmousemove = function (e) {
        el.style.left = e.pageX - disx + "px";
        el.style.top = e.pageY - disy + "px";
      };
      document.onmouseup = function () {
        document.onmousemove = document.onmouseup = null;
      };
    };
  },
  //当VNode更新的时候会执行updated，可以触发多次
  updated: function () {},
});

首先新建js文件后，写入代码，然后在配置文件plugins.js文件夹中引入该文件，最后只要在你要需要拖拽的弹窗上输入v-dialogDrag即可

参考博文：https://blog.csdn.net/PEACE_LOVE_/article/details/102955849?utm_medium=distribute.pc_relevant.none-task-blog-2~default~baidujs_baidulandingword~default-0.pc_relevant_default&spm=1001.2101.3001.4242.1&utm_relevant_index=3