How to get a index value from foreach loop in jstl

Question

I have a value set in the request object like the following,

String[] categoriesList=null;
categoriesList = engine.getCategoryNamesArray();
request.setAttribute("categoriesList", categoriesList );

and this is how I iterate in jsp page

<% if(request.getAttribute("categoriesList") != null) { %>
<c:forEach var="categoryName" items="${categoriesList}">
   <li><a onclick="getCategoryIndex()" href="#">${categoryName}</a></li>
</c:forEach>
<% }%>

How do I get index of each element and pass it to JavaScript function onclick="getCategoryIndex()".

Solution 1

use varStatus to get the index c:forEach varStatus properties

<c:forEach var="categoryName" items="${categoriesList}" varStatus="loop">
    <li><a onclick="getCategoryIndex(${loop.index})" href="#">${categoryName}</a></li>
</c:forEach>

Solution 2

I faced similar problems. After research I understand we have some more options with the varStatus="loop". It can either use a zero based index or one based index:

• The ${loop.index} uses a 0 base index
• The ${loop.count} uses a 1 base index

For Example :

<c:forEach var="currentImage" items="${cityBannerImages}" varStatus="loop">
<picture>
   <source srcset="${currentImage}" media="(min-width: 1000px)"></source>
   <source srcset="${cityMobileImages[loop.count]}" media="(min-width:600px)"></source>
   <img srcset="${cityMobileImages[loop.count]}" alt=""></img>
</picture>
</c:forEach>

For more Info please check this link.

Solution 3

You can use the varStatus attribute like this:-

<c:forEach var="categoryName" items="${categoriesList}" varStatus="myIndex">

myIndex.index will give you the index. Here myIndex is a LoopTagStatus object.

Hence, you can send that to your javascript method like this:-

<a onclick="getCategoryIndex(${myIndex.index})" href="#">${categoryName}</a>

Solution 4

This works for me:

<c:forEach var="i" begin="1970" end="2000">
    <option value="${2000-(i-1970)}">${2000-(i-1970)} 
     </option>
</c:forEach>

View more solutions

Comments

[Java Questions]

I get this Uncaught ReferenceError: myIndex is not defined and +1 for your effort

[Java Questions]

I get this Uncaught ReferenceError: loop is not defined ` and +1 for your effort

[Java Questions]

onClick of the element displayed

[newuser]

Because the varStatus value contains value upto the loop iteration. After that the value is not a valid one. so only you got the exception. For which purpose you need the index

[Java Questions]

I need to know the index[location] of each element comes in the String Array.

[Java Questions]

it works :) if I do this way onclick="getCategoryIndex(${loop.index})" ...thanks for the help

[Java Questions]

if I want to store this loop value in to a variable and pass the same to javascript method than how do I go about ?

[Java Questions]

I sued this way <input type="hidden" id="categoryIndex" name="categoryIndex" value="${category.index}"/> but it always gives me 0 when do this var categoryIndex = $('#categoryIndex').val();

[Java Questions]

created new question http://stackoverflow.com/questions/18827153/jstl-foreach-loo‌​p-setting-values-to-‌​a-hidden-variable-re‌​turns-zero-always

[newuser]

Sorry now only i saw this

[Daniel Carpio Contreras]

I think the answer is like this: <c:forEach items="${pageScope.names}" var="currentName" varStatus="status"> Family member #<c:out value="${status.count}" /> is <c:out value="${currentName}" /> <br /> </c:forEach> Check this link