--fix 持续时间为非必填

src/views/courselibrary/CoursewareManage.vue

@@ -970,7 +970,7 @@
                   :min="0"
                   :max="999999"
                   :precision="0"
-                  placeholder="请输入持续时间"
+                  :placeholder="durationText"
                   style="
                             width: 88%;
                             height: 32px;
@@ -1766,6 +1766,7 @@ import { useStore } from "vuex";
 import DropDown from "@/components/common/DropDown";
 import { checkPer, checkOwner } from "@/utils/utils";
 import dayjs from "dayjs";
+import {duration} from "moment";
 
 //列表表格
 
@@ -2184,6 +2185,7 @@ export default defineComponent({
     const CourseModalRef = ref(null);
     const store = useStore();
     const sysTypeOptions = computed(() => store.state.content_type);
+    const durationText = computed(() => state.xjkkinputV3?.length?dayjs(state.xjkkinputV3[1]).diff(dayjs(state.xjkkinputV3[0]),'minute'):'请输入持续时间');
 
     const state = reactive({
       permissions:null,
@@ -4946,6 +4948,7 @@ export default defineComponent({
       ft_exit_0,
       om_exit,
       ckxq_hs,
+      durationText,
       ftsr_exit,
       stm_exit,
       ft_exit_see,