下拉框有清空

src/components/Table/index.vue

@@ -318,6 +318,7 @@
                         v-model="tableForm[item.columnName]"
                         @change="changeSelect(item.columnName, item)"
                         placeholder="请选择"
+                        clearable
                       >
                         <el-option
                           v-for="item in tableOptions[item.columnName]"