test this point

index.js

@@ -87,9 +87,10 @@ const app=createApp({
       console.log("---------tomcat server----------");
       console.log("this.tomcat_res : "+this.tomcat_res);
       console.log("------this.books : "+this.books);
+      const books=this.books;
       // console.log("------this : "+this);
       const request = new XMLHttpRequest();
-      request.onload=function(){
+      request.onload=function(books){
         console.log("--------parse tomcat server string--------");
         const res=JSON.parse(request.responseText);
 
@@ -103,6 +104,10 @@ const app=createApp({
         console.log("res[1][\"author\"] :"+res[1]["author"]);
         console.log("this.tomcat_res : "+this.tomcat_res);
         alert("this.tomcat_res : "+this.tomcat_res);
+        
+        console.log("------books : "+books);
+        books.add(res[0]);
+        console.log("------books : "+books);
         // console.log("------this : "+this);
         console.log("this.tomcat_res : "+this.tomcat_res);
       };