JSP is a SERVER side technology. JavaScript is CLIENT side. So..in that
regard, JSP has NOTHING to do with JavaScript. However, if you are
referring to how a JSP engine parses a JSP page and if it supports
JavaScript, I can assure you it works fine. I use JavaScript form
validation on our site and there is no problem at all.
However, you cant do something like so:
<html><head>
<script language="javascript">
function js_function()
{
alert("JSP calling JavaScript");
}
</script>
</head>
<body>
<%
if( request.getParameter("some_value") )
js_function();
%>
</body>
</html>
This WONT work. Your JSP scriplet cant call a javascript function. However
you can do something like this:
<%
if( request.getParameter("some_value") )
{
%>
<script language="javascript">
js_function();
</script>
<%
}
%>
This will basically put that SCRIPT code IN the returned HTML page and call
the function "assuming" that the condition of "some_value" exists in the
request object. You have to keep in mind how JSP works. The first time you
access it, its turned into a servlet. THEN, and from then on, its accessed
no differently than a servlet. So, the first request to the JSP page passes
the request to your servlet, and more than likely (unless coming from
another page that set request "some_value" parameter) "some_value" wont
exist at that point. SO..the first request would NOT show the JS script
code, and the js_function() wouldn't be called. Now, if you have a form,
say with a hidden variable called "some_value" and you submit the form back
to the same JSP URI, at that point it WOULD find the "some_value" in the
request object, and the returned page to the browser would now include the
js_function() script call.
Kevin Duffey
Software Engineer
[EMAIL PROTECTED]
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