diff --git a/typescript/core/base.ts b/typescript/core/base.ts
index 05cc91239..3432be3ba 100644
--- a/typescript/core/base.ts
+++ b/typescript/core/base.ts
@@ -9,7 +9,7 @@ export interface _base {
 
     createWidgets: (items: any, options: any, context: any) => any;
 
-    createItems: (data: any[], innerAttr: any[], outerAttr: any[]) => any;
+    createItems: <T, U, K>(data: T[], innerAttr?: U[], outerAttr?: K[]) => (U & T & K)[];
 
     packageItems: (items: any[], layouts: any[]) => any[];