vue+element 表格复选框默认勾选第一行，只能选择一条

getLists(){
    getList().then(res=>{
        this.tableData = res.data
        // 复选框默认勾选第一行
        this.checkList = this.tableData[0]
        this.$nextTick(() => {
          this.$refs.tableRef.toggleRowSelection(this.checkList)
        })  
    })
},
changeFun(selection, row) {
   if (selection.length > 1) {
     const del_row = selection.shift()
     this.$refs.tableRef.toggleRowSelection(del_row, false)
   }
   this.checkList = selection[0]
 },