same code in coffeescript (@ preceding testMain makes it a static method and it looks like print in Dart converts to console.log)

    class HelloCoffeeTest
      @testMain: -> 
        console.log "Hello, Coffee!"
    
    HelloCoffeeTest.testMain()

resulting js

    var HelloCoffeeTest;
    HelloCoffeeTest = (function() {
      function HelloCoffeeTest() {}
      HelloCoffeeTest.testMain = function() {
        return console.log("Hello, Coffee!");
      };
      return HelloCoffeeTest;
    })();

    HelloCoffeeTest.testMain();