I’m working with a custom JSP tag file (.tag) that needs a specific JavaScript library to function properly. Right now I have to manually add the script tag for the JS file in every JSP page where I use this custom tag. This approach is really annoying and I keep forgetting to include it sometimes, which breaks the functionality.
Is there any method to automatically include the required JavaScript file from within the tag file itself? I want the JS to be loaded as a regular script import (not inline) because of browser caching benefits.
Any suggestions on how to handle this dependency management issue would be really helpful.
just put this in your .tag file: <script src='<c:url value="/path/to/your/script.js"/>'></script>. it auto loads, so you won’t forget! good for managing your scripts. hope this helps!
Here’s another way: use JSTL with conditional logic based on page context attributes. Set up a variable in your tag file that tracks if the script’s already loaded at page level (not request level). Try <c:if test="${empty pageScope.jsLibLoaded}"> then your script tag, followed by <c:set var="jsLibLoaded" value="true" scope="page"/>. This beats request scope in some cases, especially with forwards or includes. I’ve found it super helpful in legacy apps where request attributes randomly get cleared. Page scope sticks around for the entire page processing cycle and you get way more predictable behavior.
Use request attributes to prevent duplicate script inclusions. In your tag file, check if the script’s already loaded with ${requestScope['mylib_included']} - only output the script tag if it’s null. Then add <c:set var="mylib_included" value="true" scope="request"/> after the script tag. This stops multiple script tags when you use the same tag multiple times on one page. I’ve been using this approach for years - works great across different app servers. Browser caching works fine since you’re still outputting regular script tags, not inline JS.