diff --git a/javascript/README.md b/javascript/README.md
index 3626419..91e6c0f 100644
--- a/javascript/README.md
+++ b/javascript/README.md
@@ -49,7 +49,7 @@ Generates an HTML error page based on the provided parameters.
 ```typescript
 interface ErrorPageParams {
   // Basic information
-  error_code?: number;              // Default: 500
+  error_code?: string | number;     // Default: 500
   title?: string;                   // Default: 'Internal server error'
   html_title?: string;              // Default: '{error_code}: {title}'
   time?: string;                    // Auto-generated if not provided
diff --git a/javascript/src/index.ts b/javascript/src/index.ts
index f827ce8..bb0d963 100644
--- a/javascript/src/index.ts
+++ b/javascript/src/index.ts
@@ -30,7 +30,7 @@ export interface CreatorInfo {
 }
 
 export interface ErrorPageParams {
-  error_code?: number;
+  error_code?: string | number;
   title?: string;
   html_title?: string;
   time?: string;