//DSL using Node.js with Express
server {
get('/') {
    render 'Hello World!'
  }
get('/spanish') {
    render 'Hola Mundo!'
}
  get('/salute/:name') {
    render "Hello ${req.params.name}!"
  }
}.start(3000)

//Traits, operators, lists, js code
trait DomFinder {
@GsNative
private List selectItems(selector) {/*
    return $(selector).toArray();
*/}

def propertyMissing(String name) {
  selectItems("#$name") ?: selectItems(".$name")
}
}
//presenter implements DomFinder
presenter.foo.collect { it.value() }
   .findAll { it.contains 'bar' }
   .sort { it.size() }

//Groovy templates in client and server
ul {
languages.each {
      li(class: it.style) {
        yield it.name.capitalize()
    }
    if (it.photo) {
        img it.photo
    }
}
}

//Angular apps in Groovy
class TodoController implements AngularController {
  def todos = [[text:'learn grooscript', done: true]]

  def addTodo() {
  scope.todos << [text: scope.todoText, done: false]
  scope.todoText = ''
  }

  def remaining() {
  scope.todos.count { it.done }
  }

  def archive() {
  scope.todos = todos.findAll { !it.done }
  }
}

Why?

Groovy and java tools to create js apps
Enjoy js libs from a new point of view
One environment, don't repeat yourself
Gradle, Grails, Spock, Codenarc, ...
Type checking if you need it
Create Require.js modules from groovy code
@Ast's, Dsl's, scripts, traits, beans, ...
Amazing interoperability with js code
Very fast javascript code generated
Just Groovy, use js when you want to

@Component
class TodoApp {
  List<String> todos
  String actualTodo

void addTodosSubmit() {
  if (actualTodo) {
  todos << actualTodo
  setActualTodo('')
  }
  }

  void render() {
  form(id: 'addTodos') {
  h3 'TODO'
  ul {
  todos.each {
  li it
  }
  li {
  input(type: 'text', id: 'actualTodo', value: actualTodo)
  button {
  yield "Add #${todos.size() + 1}"
  }
  }
  }
  }
  }
}