test this point

index.js

@@ -86,6 +86,7 @@ const app=createApp({
     interface_web(){
       console.log("---------tomcat server----------");
       console.log("this.tomcat_res : "+this.tomcat_res);
+      console.log("------this.books : "+this.books);
       // console.log("------this : "+this);
       const request = new XMLHttpRequest();
       request.onload=function(){