elementui el-draw自定义拖拽指令

一、问题引入

场景：el-draw抽屉高度（宽度）可拖拽

二、解决方案

使用vue指令，el-draw打开后，插入一个元素，绑定鼠标事件实现拖拽

主要代码如下

/**
    * el-drawer 拖拽高度指令
    */
    Vue.directive('el-drawer-drag-height', {
      bind(el, binding, vnode, oldVnode) {
        const drawerEle = el.querySelector('.el-drawer')
        // 创建触发拖拽的元素
        const dragItem = document.createElement('div')
        // 将元素放置到抽屉的左边边缘
        dragItem.style.cssText = 'height: 5px;width: 100%;cursor: s-resize;position: absolute;top: 0;'
        drawerEle.append(dragItem)

        const moveCallback = function(e){
          // e.preventDefault();
          // e.stopPropagation();
          // 获取鼠标距离浏览器上边缘的距离
          let realHeight = document.body.clientHeight - e.pageY
          const height30 = document.body.clientHeight * 0.4
          const height80 = document.body.clientHeight * 1
          // 高度不能小于 40%
          realHeight = realHeight > height80 ? height80 : realHeight < height30 ? height30 : realHeight
          drawerEle.style.height = realHeight + 'px'
        }

        dragItem.addEventListener('mousedown', () => {
          // 拖拽时禁用文本选中
          document.body.style.userSelect = 'none'
          document.addEventListener('mousemove', moveCallback)
          document.addEventListener('mouseup',()=>{
            // 拖拽时结束时，取消禁用文本选中
            document.body.style.userSelect = 'initial'
            document.removeEventListener('mousemove', moveCallback)
            // document.removeEventListener('mouseup')
          })
        })
      }
    })