diff --git a/src/platforms/GitHub/DOMHelper.ts b/src/platforms/GitHub/DOMHelper.ts
index 7a0c776..4d2d60c 100644
--- a/src/platforms/GitHub/DOMHelper.ts
+++ b/src/platforms/GitHub/DOMHelper.ts
@@ -43,8 +43,8 @@ const selectors = {
   },
 }
 
-const getDOMJSON = (selector: string) =>
-  $(selector, e => {
+const getDOMJSON = (selector: string, _$ = $) =>
+  _$(selector, e => {
     try {
       return JSON.parse(e.textContent || '')
     } catch (error) {
diff --git a/src/utils/$.ts b/src/utils/$.ts
index aee42ef..714cc71 100644
--- a/src/utils/$.ts
+++ b/src/utils/$.ts
@@ -1,20 +1,25 @@
-export function $<E extends HTMLElement>(selector: string): E | null
-export function $<R1>(selector: string, existCallback: (element: HTMLElement) => R1): R1 | null
-export function $<R1, R2>(
-  selector: string,
-  existCallback: (element: HTMLElement) => R1,
-  otherwise: () => R2,
-): R1 | R2
-export function $<E extends HTMLElement, R2>(
-  selector: string,
-  existCallback: undefined | null,
-  otherwise: () => R2,
-): E | R2
-// eslint-disable-next-line @typescript-eslint/no-explicit-any
-export function $(selector: string, existCallback?: any, otherwise?: any) {
-  const element = document.querySelector(selector)
-  if (element) {
-    return existCallback ? existCallback(element) : element
-  }
-  return otherwise ? otherwise() : null
+export interface $ {
+  <E extends HTMLElement>(selector: string): E | null
+  <R1>(selector: string, existCallback: (element: HTMLElement) => R1): R1 | null
+  <R1, R2>(selector: string, existCallback: (element: HTMLElement) => R1, otherwise: () => R2):
+    | R1
+    | R2
+  <E extends HTMLElement, R2>(
+    selector: string,
+    existCallback: undefined | null,
+    otherwise: () => R2,
+  ): E | R2
 }
+
+export const make$ =
+  (root?: Document | HTMLElement): $ =>
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  (selector: string, existCallback?: any, otherwise?: any) => {
+    const element = (root ?? document).querySelector(selector)
+    if (element) {
+      return existCallback ? existCallback(element) : element
+    }
+    return otherwise ? otherwise() : null
+  }
+
+export const $: $ = make$()