jsp in javascript

Question

I've created a jsp page. In that when i select 1 check-box or both check-box or none, the corresponding text-boxes and list-box must be displayed in the same page.

For that i tried of calling a javascipt function when i click the checkbox. The javascript function contain code to display the textboxes. But it didn't work.

Since I'm doing this project in struts, I don't know how to get check-box value. And calling of JavaScript function works. But didn't enter into jsp code in JavaScript function.

My code is

 <tr>
 <td>SEJ:</td>
 <td>SEJ 1:<html:checkbox property="sej1" value="on" onclick="checkbox_trial()"></html:checkbox></td>
 <td>SEJ 2:<html:checkbox property="sej2" value="on" onclick="checkbox_trial()"></html:checkbox></td>
 </tr>


  <script type="text/javascript">
  function checkbox_trial()
  {

        <% if(request.getParameter("sej1")=="on"){
    %> 
   <tr><td>SEJ1 Age<html:text property="sej1_age"></html:text></td></tr>
   <tr><td>SEJ1 DOI<html:text property="sej1_doi"></html:text></td></tr>
   <%} 

       else if(request.getParameter("sej2")=="on"){%>
   <tr><td>SEJ2 Age<html:text property="sej2_age"></html:text></td></tr>
       <tr><td>SEJ2 DOI<html:text property="sej2_doi"></html:text></td></tr>
   <%}

       else if((request.getParameter("sej1")=="on")&&(request.getParameter("sej2")=="on")){%>
   <tr><td>SEJ1 Age<html:text property="sej1_age"></html:text></td></tr>
   <tr><td>SEJ1 DOI<html:text property="sej1_doi"></html:text></td></tr>
   <tr><td>SEJ2 Age<html:text property="sej2_age"></html:text></td></tr>
   <tr><td>SEJ2 DOI<html:text property="sej2_doi"></html:text></td></tr>
   <%}

       else{%>
   NOTHING <% } %>
  }

You wanna post some code so we have something to refer to when trying to answer your question? Specifically, we need to see HTML and JavaScript, and just the relevant parts. Please don't post your entire project ;) — jamesmortensen, Jan 17 '11 at 02:49

BalusC · Accepted Answer · 2011-01-17T03:17:24.513

3

This is how it works: Java/JSP runs at webserver, produces HTML/CSS/JS, webserver sends it to webbrowser, webbrowser runs HTML/CSS/JS. Not Java/JSP. Rightclick the page in webbrowser and choose View Source. If Java/JSP has done its job right, you shouldn't see any line of it in there.

If you want to invoke Java/JSP code using JavaScript, you've got to invoke another HTTP request to the webserver so that it can execute the Java/JSP code based on the specific request. You can do that by either submitting the form or firing an asynchronous (ajaxical) request.

Given the skills shown as far and the fact that you're using Struts, I think ajax is going to be a bit too complex. I'd suggest to just submit the form on click of the checkbox

<input type="checkbox" name="show" value="true" onclick="submit()" />

and then let JSP conditionally display the input fields (just a JSTL example since I don't do Struts)

<c:if test="${param.show == 'true'}">
    <input type="text" />
    <select />
</c:if>

Update: you've by the way another major problem in the code. You can't compare string values by == in Java code (you can do so in EL only). In Java code you need to use equals() method. Otherwise they will be compared by reference instead of by value. I'd suggest to learn basic Java as well.

edited Jan 17 '11 at 03:17

answered Jan 17 '11 at 02:53

BalusC

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Ugly solution - but I agree based on OP's question (lack of experience) that this is probably best. I definitely recommend OP eventually learn to use AJAX. – jamesmortensen Jan 17 '11 at 03:02
Regardless, if the OP is interested, my answer on [this question](http://stackoverflow.com/questions/4114742/simple-calculator-in-jsp) contains a nice example for the first Ajax steps. However, it's not Struts targeted. – BalusC Jan 17 '11 at 03:03
hi Balu, is it possible for you to explain the first line of JSTL example. Since i'm new to it, i cant understand – Pavalesh Jan 17 '11 at 03:14
It basically says, "if the value of the request parameter with the name "show" equals to "true", then show the following content". In *scriptlet*, it's the same as `if (request.getParameter("show").equals("true"))` (including a nullcheck). JSTL/EL was a decade ago introduced to replace *scriptlets*. See also [How to avoid Java code in JSP files?](http://stackoverflow.com/questions/3177733/how-to-avoid-java-code-in-jsp-files) – BalusC Jan 17 '11 at 03:16
Is it possible to have this jstl code and checkbox creation code in the same jsp page. Actually i want to display the textboxes in the same page as the checkbox is clicked – Pavalesh Jan 17 '11 at 04:40

jsp in javascript

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