Question

Can anybody tell me how to assign javascript variables to jsp request or to jsp session.

I am doing something like this

Here deletedRows is a hidden field.

var del=45;
document.getElementById("deletedRows").value=del
alert(document.getElementById("deletedRows").value);
<%String del_values = request.getParameter("deletedRows");%>
<%request.getSession().setAttribute("del_rows", del_values);%>

I don’t get the value of del in my servlet.

Answer 1

JSP gets compiled on the server. All the client gets is the “output” of the JSP: the HTML, CSS and Javascript.

The Javascript gets executed after this. Meaning everything in the JSP has become HTML et all when the javascript executes. You way want to think this as the Java/JSP part has “completed” and now the HTML/Javascript part takes over.

Now you want to pass on some value calculated/manipulated via Javascript back to the server. (I think this is what you mean when you say “assingn javascript variables to jsp request or to jsp session”

For this you have to submit the page to the server, and these values should be part of the form that is being submitted.

You may already have these values in some HTML elements (like a <input> or <select>), if not you can create hidden elements and populate these with the values before submitting the <form>.

In the code you have provided, you are populating the hidden field correctly, but you have to retrieve the value in the servlet, not in the JSP itself. Also, make sure that the hidden field in in a <form> and that form is submitted.

Once the form is submitted (to a servlet) the values can be retrieved in the servlet via request.getParameter.

There are few other mechanisms to send a value to the server, using a URL parameter or via Asynchronous (AJAX) requests, but I am not sure whether you are looking at these also.