CoffeeScript
CoffeeScript is a seriously awesome client-side scripting language that fixes the many warts of Javascript.
Full usage guide
Because CoffeeScript is an external project, we won’t attempt to reproduce its documentation here. Go to the official documentation; you’ll be glad you did!
Set up CoffeeScript in Scalatra
Install
Install the plugin by adding the dependency to your project/plugins.sbt
:
resolvers += Resolver.url("sbt-plugin-snapshots",
new URL("http://scalasbt.artifactoryonline.com/scalasbt/sbt-plugin-snapshots/"))(
Resolver.ivyStylePatterns)
addSbtPlugin("com.bowlingx" %% "xsbt-wro4j-plugin" % "0.1.0-SNAPSHOT")
Enable
Add these imports to the very top of your build.sbt
:
import com.bowlingx.sbt.plugins.Wro4jPlugin._
import Wro4jKeys._
Now enable to plugin by adding these lines to your build.sbt
, after all your imports.
Don’t attempt to remove the blank line!
seq(wro4jSettings: _*)
(webappResources in Compile) <+= (targetFolder in generateResources in Compile)
Configure
Unfortunately, the plugin we’re using does require a bit of configuration.
Create the file src/main/webapp/WEB-INF/wro.xml
, telling the compiler where our
CoffeeScript files are:
<?xml version="1.0" encoding="UTF-8"?>
<groups
xmlns="http://www.isdc.ro/wro"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.isdc.ro/wro wro.xsd"
>
<group name="scripts">
<js>/coffee/*.coffee</js>
</group>
</groups>
Also create the file src/main/webapp/WEB-INF/wro.properties
, requesting CoffeeScript
compilation:
preProcessors = coffeeScript
postProcessors =
Example
With installation out of the way, you’re free to put your CoffeeScript files in
src/main/webapp/coffee
.
It doesn’t matter what the file/s are called, so long as they have the .coffee
extension we said we’d use in the wro.xml
configuration.
For example, create src/main/webapp/less/main.coffee
, which shows off the
optionality of parentheses and semicolons in CoffeeScript:
alert "Hello CoffeeScript!"
That file will be compiled to one called compiled/scripts.js
, so you can refer to it
in your app like this:
class CoffeeScriptApp extends ScalatraServlet {
get("/") {
<html>
<body>
<h1>This is
<a href="http://scalatra.org/2.2/guides/resources/coffeescript.html">resources/coffeescript</a>!
</h1>
<script type="text/javascript" src="compiled/scripts.js"></script>
</body>
</html>
}
}
See it in action
Now compile and run your app as usual. If all has gone well, and you’ve used the above example, an annoying popup should launch on page load.
$ cd scalatra-coffeescript
$ ./sbt
> container:start
> browse
If browse
doesn’t launch your browser, manually open
http://localhost:8080/ in your browser.
Further documentation
The resources processor we’ve been using, wro4j, is extensively configurable. See the wro4j documentation for more information.