alert.coffee

->
  alert('Hello World!')

alert.js

(function() {
  return alert('Hello World!');
});

alert_array.coffee

alert_array = (array) ->
  for element, i in array
    alert element

alert_array.js

var alert_array;

alert_array = function(array) {
  var element, i, _len, _results;
  _results = [];
  for (i = 0, _len = array.length; i < _len; i++) {
    element = array[i];
    _results.push(alert(element));
  }
  return _results;
};

alert_parameter.coffee

alert_parameter = (array) ->
  alert array

alert_parameter.js

alert_parameter = function(array) {
  return alert(array);
};