diff --git a/src/platforms/GitHub/DOMHelper.ts b/src/platforms/GitHub/DOMHelper.ts
index 43e8f14..c9c386b 100644
--- a/src/platforms/GitHub/DOMHelper.ts
+++ b/src/platforms/GitHub/DOMHelper.ts
@@ -31,7 +31,7 @@ export function isInCodePage() {
 }
 
 export function getIssueTitle() {
-  const title: string | undefined = $('.gh-header-title')?.textContent
+  const title = $('.gh-header-title')?.textContent
   return title?.trim().replace(/\n/g, '')
 }
 
@@ -40,7 +40,7 @@ export function getCurrentBranch(passive = false) {
     '.repository-content #branch-select-menu summary',
     '.repository-content .branch-select-menu summary',
   ].join()
-  const branchButtonElement: HTMLElement = $(selectedBranchButtonSelector)
+  const branchButtonElement = $(selectedBranchButtonSelector)
   if (branchButtonElement) {
     const branchNameSpanElement = branchButtonElement.querySelector('span')
     if (branchNameSpanElement) {
diff --git a/src/platforms/Gitea/DOMHelper.ts b/src/platforms/Gitea/DOMHelper.ts
index d5ae608..acd7043 100644
--- a/src/platforms/Gitea/DOMHelper.ts
+++ b/src/platforms/Gitea/DOMHelper.ts
@@ -13,12 +13,11 @@ export function isInCodePage() {
 
 export function getCurrentBranch() {
   const branchListSelector = '.reference'
-  const branchButtonElement: HTMLElement = $(branchListSelector)
-  const branchNameElement = branchButtonElement.querySelector('.text > strong')
+  const branchButtonElement = $(branchListSelector)
+  const branchNameElement = branchButtonElement?.querySelector('.text > strong')
   if (branchNameElement) {
-    return branchNameElement.textContent;
+    return branchNameElement.textContent
   }
 
   raiseError(new Error('cannot get current branch'))
 }
-
diff --git a/src/platforms/Gitee/DOMHelper.ts b/src/platforms/Gitee/DOMHelper.ts
index 4b99612..2075b56 100644
--- a/src/platforms/Gitee/DOMHelper.ts
+++ b/src/platforms/Gitee/DOMHelper.ts
@@ -15,14 +15,11 @@ export function isInCodePage() {
 }
 
 export function getCurrentBranch() {
-  const selectedBranchButtonSelector = '#git-project-branch'
-  const branchButtonElement: HTMLElement = $(selectedBranchButtonSelector)
-  if (branchButtonElement) {
-    const branchNameSpanElement = branchButtonElement.querySelector('.text')
-    if (branchNameSpanElement) {
-      const partialBranchNameFromInnerText = branchNameSpanElement.textContent
-      if (!partialBranchNameFromInnerText?.includes('…')) return partialBranchNameFromInnerText
-    }
+  const selectedBranchButtonSelector = '#git-project-branch .text'
+  const element = $(selectedBranchButtonSelector)
+  if (element) {
+    const partialBranchNameFromInnerText = element.textContent
+    if (!partialBranchNameFromInnerText?.includes('…')) return partialBranchNameFromInnerText
   }
 
   raiseError(new Error('cannot get current branch'))
diff --git a/src/utils/DOMHelper.ts b/src/utils/DOMHelper.ts
index 38f9fcd..8651b7a 100644
--- a/src/utils/DOMHelper.ts
+++ b/src/utils/DOMHelper.ts
@@ -26,20 +26,22 @@ export function setBodyIndent(shouldShowGitako: boolean) {
   }
 }
 
-export function $<EE extends Element, E extends (element: EE) => any, O extends () => any>(
+export function $(selector: string): HTMLElement | null
+export function $<T1>(selector: string, existCallback: (element: HTMLElement) => T1): T1
+export function $<T1, T2>(
   selector: string,
-  existCallback?: E,
-  otherwise?: O,
-): E extends never
-  ? O extends never
-    ? Element | null
-    : ReturnType<O> | null
-  : O extends never
-  ? ReturnType<E> | null
-  : ReturnType<O> | ReturnType<E> {
+  existCallback: (element: HTMLElement) => T1,
+  otherwise: () => T2,
+): T1 | T2
+export function $<T2>(
+  selector: string,
+  existCallback: undefined | null,
+  otherwise: () => T2,
+): HTMLElement | null | T2
+export function $(selector: string, existCallback?: any, otherwise?: any) {
   const element = document.querySelector(selector)
   if (element) {
-    return existCallback ? existCallback(element as EE) : element
+    return existCallback ? existCallback(element) : element
   }
   return otherwise ? otherwise() : null
 }