userei getParameter

codice:
getParameter
public String getParameter(String name)Returns the value of the named parameter in the HTML tag. For example, if this applet is specified as 
 <applet code="Clock" width=50 height=50>
 <param name=Color value="blue">
 </applet>
 then a call to getParameter("Color") returns the value "blue".
il parametro lo scriverei con js