diff --git a/src/App.vue b/src/App.vue
index 77079331ed9e19e5d42dd55a512e4ec56860cc68..7def2c3bfb74ea038e4b788ea27afb2f9714e444 100644
--- a/src/App.vue
+++ b/src/App.vue
@@ -547,9 +547,9 @@ export default {
     },
     addTocClickToBody() {
       document.querySelector("body").addEventListener("click", function(e) {
-        if (!e.target?.className.includes("md_toc_item")) return;
+        if (!e.target.className.includes("md_toc_item")) return;
         const targetEl = document.getElementById(
-          e.target?.getAttribute("href")
+          e.target.getAttribute("href")
         );
         if (!targetEl) return;
         targetEl.scrollIntoView({
diff --git a/src/assets/js/utils.js b/src/assets/js/utils.js
index 6386d1fbb4c36ae65dbaf64b58b05213d87ed21b..7cea4cca5fb89e986df463847b784e1ab6819fb0 100644
--- a/src/assets/js/utils.js
+++ b/src/assets/js/utils.js
@@ -184,7 +184,7 @@ export function isNotFalse(val) {
 }
 
 export function pick(list, ...arg) {
-  if (!list.length || !arg?.length) return;
+  if (!list.length || !(arg && arg.length)) return;
   return list.filter(item => {
     return arg.find(key => key === item.name);
   });
diff --git a/src/components/content/components/toc-doc.vue b/src/components/content/components/toc-doc.vue
index 84effb9f9aeb33ac7f8a7a18ca6659bf8dc4bff7..fd3cd6175c30459babab039ee48a26e01e4615ae 100644
--- a/src/components/content/components/toc-doc.vue
+++ b/src/components/content/components/toc-doc.vue
@@ -59,7 +59,7 @@ export default {
   },
   computed: {
     topList() {
-      return this.dirTags.map(item => Math.abs(item?.top));
+      return this.dirTags.map(item => Math.abs(item && item.top));
     }
   },
   created() {
@@ -92,7 +92,9 @@ export default {
       // ).scrollTop = targetOffsetTop;
     },
     dirItemActive(item) {
-      const itemScrollTop = document.getElementById(item.id)?.offsetTop;
+      const targetEl = document.getElementById(item.id);
+      if (!targetEl) return;
+      const itemScrollTop = targetEl.offsetTop;
       const top = this.scrollBarTop - itemScrollTop;
       this.$set(item, "top", top);
       return Math.abs(top) === Math.min(...this.topList);
diff --git a/src/components/content/mixins/render-mixins.js b/src/components/content/mixins/render-mixins.js
index 7b462350f187ef96c6bc86ec8e7ade07989c7d2e..bdcc64a4d86975b41de531f0a64d236ce0fb2df0 100644
--- a/src/components/content/mixins/render-mixins.js
+++ b/src/components/content/mixins/render-mixins.js
@@ -142,7 +142,7 @@ export default {
           return "<h" + level + ">" + text + "</h" + level + ">\n";
         },
         link(href, title, text) {
-          if (text?.toLowerCase() === "toc") {
+          if (text && text.toLowerCase() === "toc") {
             return `
             <h1 class="toc_title">${href}</h1>
             <div class="tocEl"></div>`;
diff --git a/src/main.js b/src/main.js
index 1701001d1b4eb19030023d341487a0f6ac7afcb0..f1e7350c2641fedc9c05105854f6dcc13661ec3a 100644
--- a/src/main.js
+++ b/src/main.js
@@ -4,10 +4,6 @@ import Vtip from "vtip";
 import "vtip/lib/index.min.css";
 import { initStyle, setzIndex, isNotEmpty } from "@/assets/js/utils";
 import "@/assets/style/global.less";
-// import "@/assets/jupyter-render/dist/index.js";
-// import "@/assets/jupyter-render/dist/assets/index.css";
-
-
 Vue.use(Vtip.directive);
 
 function initMdEditor(obj) {