vue element ui树形结构table级联选择问题

Question

一个树形结构table，想勾选子级的时候父级的选择框被半勾选上，像全选框那样，子级选中父级被勾选上的操作已经实现，应该如何修改成半选，感谢各位

 <el-table
        ref="multipleTable"
        :data="helpData"
        :header-cell-style="{ 'text-align': 'center' }"
        :cell-style="{ 'text-align': 'center' }"
        :height="tableHeight"
        style="max-height: 528px;"
        v-loading="helpDataStatus"
        highlight-current-row
        @select="handleSelect"
        @select-all="handleSelectAll"
        @row-click="handleCurrentHelpTable"
        @selection-change="handleSelectionChange"
        row-key="id"
        :tree-props="{ children: 'children', hasChildren: 'hasChildren' }"
      >

所有的级联操作

// 全选操作
     handleSelectAll() {
      const isAllSelected = this.$refs.multipleTable.store.states.isAllSelected;
      var _handleSelectAll = (data) => {
        data.forEach(item => {
          this.$refs.multipleTable.toggleRowSelection(item, isAllSelected)
          _handleSelectAll(item.children || [])
        })
      }
      _handleSelectAll(this.helpData)
    },
    // 勾选数据事件
    handleSelect(selection, current) {
      // 判断selection中是否存在current,若是存在那么就代表是被勾选上了,若是不存在代表是取消勾选了
      const isChecked = !!selection.find((item) => item.id === current.id)
      if (!isChecked) {
        // 那么其所有的祖先也应该被取消勾选
        this.uncheckedParents(selection, current)
        // 那么其所有的后代也应该被取消勾选
        this.toggleCheckedChildrens(selection, current, false)
      } else {
        // 如果当前项被勾选
        // 那么若同一组的元素都被勾选了,那么父元素将也被勾选,依次往上类推
        // this.checkedParents(selection)
        // 那么其所有的后代都要被勾选
        this.toggleCheckedChildrens(selection, current, true)
      }
      console.log(selection, current, 'selection,current')
    },
    // 勾选子级
    toggleCheckedChildrens(selection, item, isChecked) {
      var _toggleCheckedChildrens = (data) => {
        data.find((element) => {
          this.$refs.multipleTable.toggleRowSelection(element, isChecked)
          if (isChecked && !selection.find((item) => item.id === element.id)) {
            selection.push(element)
          } else if (
            !isChecked &&
            selection.find((item) => item.id === element.id)
          ) {
            for (let i = selection.length - 1; i >= 0; i--) {
              if (selection[i].id === element.id) {
                selection.splice(i, 1)
                break
              }
            }
          }
          _toggleCheckedChildrens(element.children || [])
        })
      }
      _toggleCheckedChildrens(item.children || [])
    }, 
    // 选中子级，勾选父级
    checkedParents(selection) {
      var _checkedParents = (element) => {
        const children = element.children
        if (children && children.length) {
          // 如果某一条子级被选中,返回
          const anyChildrenChecked = children.some((child) => {
            return _checkedParents(child)
          })
          // 如果所有子级被选中，返回
          const allChildrenChecked = children.every((child) => {
            return _checkedParents(child)
          })
          //   如果所有子节点被选中，父节点也被选中
          if (allChildrenChecked) {
            this.$refs.multipleTable.toggleRowSelection(element, true)
            if (!selection.find((item) => item.id === element.id)) {
              selection.push(element)
            }
          }
          // 如果任意一个子节点被选中，父节点也被选中
          if (anyChildrenChecked) {
            console.log(element,'-=-=-=-=-=-=-=')
            this.$refs.multipleTable.toggleRowSelection(element, true)
            if (!selection.find((item) => item.id === element.id)) {
              selection.push(element)
            }
          }
        }
   
        return selection.find((item) => item.id === element.id)
      }
      this.helpData.forEach((element) => {
        // 导入每一条数据
        _checkedParents(element)
      })
    },
    uncheckedParents(selection, item) {
      var _uncheckedParents = (data) => {
        return data.find((element) => {
          if (element.id === item.id) {
            return true
          } else if (_uncheckedParents(element.children || [])) {
            this.$refs.multipleTable.toggleRowSelection(element, false)
            for (let i = selection.length - 1; i >= 0; i--) {
              if (selection[i].id === element.id) {
                selection.splice(i, 1)
                break
              }
            }
            return true
          } else {
            return false
          }
        })
      }
      _uncheckedParents(selection)
    },