Abstract: A proxy server device adds, to a script in the document data of a Web page that is transmitted from a Web server device to a terminal device, a code Y that instructs an event generation of script execution, and, once a script X, which modifies a DOM tree of a Web page displayed according to the document data according to predetermined rules, has been added to the document data, transmits the document data to a terminal device. The terminal device generates an event according to code Y in compliance with the execution of a script included in the received document data. The terminal device modifies the DOM tree according to script X in compliance with predetermined rules, by using the event as a trigger. The terminal device displays a Web page according to the modified DOM tree.

Abstract: In ordinary mode, a virtual proxy server acquires, from a web server, display instruction data that instructs the display of a webpage, in accordance with a request from a web browser, and delivers the display instruction data to web browser. The web browser displays a webpage according to the display instruction data acquired from virtual proxy server, and stores document data of the display instruction data in a storage device. In editing mode, the virtual proxy server acquires, from storage device, components specified by a user from the display instruction data, in accordance with a request from the web browser, acquires other components from the web server, and delivers the components to the web browser. The web browser performs a test display of a webpage that is being modified, according to display instruction data acquired from virtual proxy server.