WebJars-Taglib

Introduction

This project contains a simple taglib for locating WebJars resources without knowing their full path. Typical usage is to avoid embedding the version number of your libs in JSP pages.

The simplest usage is shown below:

<%@ taglib uri="http://www.webjars.org/tags" prefix="wj"%>

<wj:locate path="bootstrap.css" />

will output something like

/bootstrap/2.3.1/css/bootstrap.css

If you prefer assigning a variable with the path, simply add the var attribute and use that variable in your JSP page either like this (using for example Spring's <url /> tag):

<wj:locate path="bootstrap.css" var="v"/>
<link href="<s:url value='/webjars${v}' />" rel="stylesheet">

or like this

<wj:locate path="bootstrap.css" var="v">
    <link href="<s:url value='/webjars${v}' />" rel="stylesheet">
</wj:locate>

Matching multiple resources

It is possible to match several resources and iterate over each result, using the prefix attribute instead of path:

<wj:locate prefix="/bootstrap" var="v">
	<%-- Do something with ${v}--%>
</wj:locate>

Advanced usage

There are other attributes one can use, namely:

Omit file extension

<wj:locate path="bootstrap.css" omitExtension="false" />

will output something like

/bootstrap/2.3.1/css/bootstrap

instead of

/bootstrap/2.3.1/css/bootstrap.css

This is useful e.g. when using require.js

Controlling variable exposition scope

By default, the path is emitted as an attribute with page scope. If you want to use another scope, simply use the scope attribute with values request, session or application:

<wj:locate path="bootstrap.css" var="v" scope="session" />

Changing the relative root for results

The default behavior is to remove the META-INF/resources/webjars prefix from resource paths. If you want to emit paths with a longer (or shorter) prefix, just change that value thru the use of the relativeTo attribute:

<wj:locate path="bootstrap.css" relativeTo="META-INF/resources" />

will output something like

/webjars/bootstrap/2.3.1/css/bootstrap

Making dependencies version agnostic

Since version 0.3, it is possible to reference resources contained in any WebJar (such as javascript and css files) without specifying the version number. To do so, you may reference a WebJar asset in your JSP like this:

<wj:locate webjar="bootstrap" path="css/bootstrap.css" />

will output something like

/bootstrap/2.3.1/css/bootstrap.css

Be sure to remove ONLY the version from the path, and to specify the EXACT full path to the resource.