I just added a button below the applet. Click get[b] x,t data[/b] button after the simulations is paused.
You wll find (x,t) value in the textarea. You can copy and paste those value into excel to create a plot.
Actually, if you download the ejs source code and open it with latest EJS.
You can get data sets automatically when you run it as an application. You can manipulate or plot data in many ways. Try it!