This plugin lets you use Groovy expressions in your Javascript and CSS asset files and participates in the Grails Asset Pipeline Plugin pre-compilation.
This lets you get access to config and environment variables during the pre-compilation process so that you can easily serve up static files with content that is crafted for that application.
You get the grailsApplication and config objects injected into the binding for when expressions are evaluated:
ex:
Confg.groovy
...
grails.serverURL = "https://mycompany.com/"
...
application.js-gtpl:
//= require_self
var serverURL = "${config.grails.serverURL}";
creates application.js:
//= require_self
var serverURL = "https://mycompany.com/";
You can also execute more complicated expressions inside <% ... %> blocks, see the jasmine tests for more examples.
NB: be sure to make sure when you build your war file that you're using the right environment to get the correct values out of Config.groovy.
Currently, there is support for javascript files (with the extension .js-gtpl) and CSS files (with the extension .css-gtpl).
Some scenarios that this plugin enables:
- extracting the base path for urls out of config, so you can refer to asset paths in JS/CSS at
/your-app/<filepath>in dev but at just/<filepath>in test/prod environments. - creating a javascript array to hold your enum values for drop-downs and radio buttons
- putting a timestamp/version/git hash in a comment in your assets so you can easily tell when they were built
All of these things are possible without this plugin by doing a callback to the server, or within a script block inside your GSP files, but those are slower, clunkier solutions.