diff --git a/simple-mind-map/src/core/event/Event.js b/simple-mind-map/src/core/event/Event.js
index b81d95e6..0a5f2ad5 100644
--- a/simple-mind-map/src/core/event/Event.js
+++ b/simple-mind-map/src/core/event/Event.js
@@ -99,7 +99,6 @@ class Event extends EventEmitter {
 
   //  鼠标按下事件
   onMousedown(e) {
-    e.preventDefault()
     // 鼠标左键
     if (e.which === 1) {
       this.isLeftMousedown = true
@@ -115,7 +114,6 @@ class Event extends EventEmitter {
 
   //  鼠标移动事件
   onMousemove(e) {
-    e.preventDefault()
     let { useLeftKeySelectionRightKeyDrag } = this.mindMap.opt
     this.mousemovePos.x = e.clientX
     this.mousemovePos.y = e.clientY
diff --git a/web/src/pages/Edit/components/FormulaSidebar.vue b/web/src/pages/Edit/components/FormulaSidebar.vue
index 6ee47d2e..bf8217b5 100644
--- a/web/src/pages/Edit/components/FormulaSidebar.vue
+++ b/web/src/pages/Edit/components/FormulaSidebar.vue
@@ -80,6 +80,7 @@ export default {
     ...mapMutations(['setActiveSidebar']),
 
     init() {
+      if (!window.katex) return
       this.list = formulaList.map(item => {
         return {
           overview: window.katex.renderToString(
diff --git a/web/src/pages/Edit/components/Navigator.vue b/web/src/pages/Edit/components/Navigator.vue
index 530bcfea..fe5424a6 100644
--- a/web/src/pages/Edit/components/Navigator.vue
+++ b/web/src/pages/Edit/components/Navigator.vue
@@ -169,7 +169,7 @@ export default {
       if (!this.withTransition) {
         this.withTransition = true
       }
-      this.mindMap.miniMap.onMouseup(e)
+      if (this.mindMap.miniMap) this.mindMap.miniMap.onMouseup(e)
     },
 
     // 视口框的鼠标按下事件