Web applications often rely on server-side scripts to handle HTTP requests, to generate dynamic contents, and to interact with other components. The server-side scripts usually mix with HTML statements and are difficult to understand and test. In particular, these scripts do not have any compiling check and could be error-prone. Thus, it becomes critical to test the server-side scripts for ensuring the quality and reliability of Web applications. We adapt traditional dataflow testing techniques into the context of Java Server Pages (JSP), a very popular server-side script for developing Web applications with Java technology. We point out that the JSP implicit objects and action tags can introduce several unique dataflow test artifacts which need to be addressed. A test model is presented to capture the dataflow information of JSP pages with considerations of various implicit objects and action tags. Based on the test model, we describe an approach to compute the intraprocedural and interprocedural data flow test paths for uncovering the data anomalies of JSP pages.