npm install vuedraggable --save

import Vue from 'vue';
 
// v-dialogDrag: 弹窗拖拽属性
Vue.directive('dialogDrag', {
    bind(el, binding, vnode, oldVnode) {
        const dialogHeaderEl = el.querySelector('.el-dialog__header');
        const dragDom = el.querySelector('.el-dialog');
 
        dialogHeaderEl.style.cssText += ';cursor:move;'
        dragDom.style.cssText += ';top:0px;'
 
        // 获取原有属性 ie dom元素.currentStyle 火狐谷歌 window.getComputedStyle(dom元素, null);
        const sty = (() => {
            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 screenWidth = document.body.clientWidth; // body当前宽度
            const screenHeight = document.documentElement.clientHeight; // 可见区域高度(应为body高度，可某些环境下无法获取)
 
            const dragDomWidth = dragDom.offsetWidth; // 对话框宽度
            const dragDomheight = dragDom.offsetHeight; // 对话框高度
 
            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 = sty(dragDom, 'left');
            let styT = sty(dragDom, 'top');
 
            // 注意在ie中 第一次获取到的值为组件自带50% 移动之后赋值为px
            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;`;
            };
 
            document.onmouseup = function (e) {
                document.onmousemove = null;
                document.onmouseup = null;
            };
        }
    }
})

<el-dialog
    v-dialogDrag
    :title="dialogTitle"
    :visible.sync="addDialogVisible"
    :before-close="handleClose"
    :close-on-click-modal="false"
    width="50%">
    <div class="add_columns">
        <div class="pull-organize">
            <div class="bm-title">部门管理</div>
            <el-tree
                :data="treeData"
                lazy:load="loadNode"
                accordion 
                :props="defaultProps"
                :default-expand-all="false">
            </el-tree>
        </div>
        <div class="show-information">
            <el-form inline>
                <el-form-item label="用户ID">
                    <el-input v-model="searchParams.userId" size="mini" ></el-input>
                </el-form-item>
                <el-form-item label="用户名">
                    <el-input v-model="searchParams.userName" size="mini"></el-input>
                </el-form-item>
                <el-form-item class="btn-item">
                    <el-button type="primary" @click="handleQuery" size="mini">查询</el-button>
                </el-form-item>
                    <el-form-item class="btn-item">
                    <el-button type="success" @click="hadnleAddPerson" size="mini">添加人员</el-button>
                </el-form-item>
            </el-form>
            <el-table
                :data="tableData"
                class="oneTabel"
                style="width:100%;">
                <el-table-column type="selection" width="50"></el-table-column>
                <el-table-column prop="id" width="60" label="登录ID"></el-table-column>
                <el-table-column prop="userName" label="用户名"></el-table-column>
                <el-table-column prop="education" label="部门"></el-table-column>
                <el-table-column prop="sex" label="手机"></el-table-column>
            </el-table>
        </div>
    </div>
</el-dialog>