How can I access Java list elements from my client-side JavaScript code?

Question

I have the following simple script, which I am using to dynamically create the list elements in a <ul>

<script type="text/javascript">
    function generate(){
        var arr = new Array();
        <c:forEach items="${articles}" var="a" varStatus="status">
            $('#listitems').append(
                "<li>"+${a.title}+"</li>"
            );
            arr[${status.index}] ="${a.slideShow.images}";
        </c:forEach>
    }
</script>

My problem stems from the images attribute. Every article has a slideshow and every slideshow has a list of images. I want to pull out the very first image from the list of images via the jave list.get(index); I want to do something like "${a.slideShow.images.get(0)}";. The get() is a java method from the list object.

Any ideas?

Javascript is in no way related to Java, apart from the first four letters of the name. — Adam Robinson
– Adam Robinson, Commented Feb 12, 2010 at 18:45
Forget about Java, use plain (real javascript), and DOM (Document Object Model) to get the items in that UL. JavaScript is also typically client side code. — JL.
– JL., Commented Feb 12, 2010 at 18:46
Guys, read the question and code instead of only title before commenting. — BalusC
– BalusC, Commented Feb 12, 2010 at 19:00
Titles are important. Are they not a synopsis of the problem? If the question states something different than the prose, might it not suggest a misunderstanding? — Upperstage
– Upperstage, Commented Feb 12, 2010 at 19:03
Hi guys, I'm terrably sorry about the ambiguous wording. BalusC, point well taken. Thanks for the help. — Faiyet
– Faiyet, Commented Feb 17, 2010 at 14:11

BalusC · Accepted Answer · 2010-02-12 18:59:40Z

5

In EL you can use the brace notation to access a List element by index. Thus, the following should do:

arr[${status.index}] = "${a.slideShow.images[0]}";

This will behind the scenes do exactly as you proposed: a.getSlideShow().getImages().get(0).

That said, you normally declare JS arrays like follows:

var arr = [];

The new keyword is considered discouraged in JS.

edited Feb 12, 2010 at 18:59

answered Feb 12, 2010 at 18:54

BalusC

1.1m377 gold badges3.7k silver badges3.6k bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Upperstage Over a year ago

new keyword discouraged for creating arrays? Or always discouraged?

BalusC Over a year ago

@Upper Stage: stackoverflow.com/questions/383402/…

BalusC Over a year ago

@Binaryrespawn: What do you mean with "causing my page not to load"? This is too ambiguous. If you get a blank page, check server logs for any exceptions/errors. If you get a normal page, but the images doesn't get loaded, rightclick page and view generated HTML/JS source code and verify if it is syntactically valid.

Faiyet Over a year ago

Hi,this stsatement did not work for me. It causes my page not to load, may be because there are articles with no slideshow and hence no images. Hence I did this, <c:if test="${a.slideShow.images != null}>arr[${status.index}] = ${a.slideShow.images[0]};</c:if> , but this causes my page not to load. and its the part where it said images[0]. Now the concept works, because, as a test, I tried ${articles[0].title} within the body and this worked. So I am really baffeled.

BalusC Over a year ago

As said, just open page in browser and check generated JS code if it is syntactically valid. Maybe it represents a string value and you're forgotten singlequotes around the JS variable value.

Upperstage · Accepted Answer · 2010-02-12 18:48:50Z

1

As those who commented on your question suggest, this is a common misunderstanding. By the time your JavaScript executes (in the browser), Java and JSP and JSTL are no longer available. The JSTL/JSP execute at the server to create source/HTML that is then sent to the client.

View source on your page - it might shed some light. You should not see the JSP/JSTL you include above.

answered Feb 12, 2010 at 18:48

Upperstage

3,7678 gold badges47 silver badges69 bronze badges

1 Comment

Upperstage Over a year ago

You are correct. By the wording of the question and the attached comments, I was not certain he understood that. Do you think my answer is confusing?

Collectives™ on Stack Overflow

How can I access Java list elements from my client-side JavaScript code?

2 Answers 2

5 Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

5 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related