Question

I ve been looking at CoffeeScript and I m not understanding how you would write code like this. How does it handle nested anonymous functions in its syntax?

;(function($) {
          var app = $.sammy(function() {

            this.get( #/ , function() {
              $( #main ).text(  );
            });

            this.get( #/test , function() {
              $( #main ).text( Hello World );
            });

          });

          $(function() {
            app.run()
          });
        })(jQuery);

Answer 1

didn t actually compile it, but this should work

(($) ->
  app = $.sammy ->

    this.get  #/ , ->
      $( #main ).text    

    this.get  #/test , ->
      $( #main ).text  Hello World 

  $(->
    app.run()
  )
)(jQuery);

Answer 2

Matt s answer is correct, but here s an alternative method:

In CoffeeScript 1.0 (released a few weeks after this question was posed), a do operator was introduced that runs the function that immediately follows it. It s mostly used for capturing variables in loops, since

for x in arr
  do (x) ->
    setTimeout (-> console.log x), 50

(which passes a reference to x into the anonymous function) behaves differently than

for x in arr
  setTimeout (-> console.log x), 50

The latter will simply output the last entry in arr repeatedly, since there s only one x.

Anyway, you should be aware of do as a way of running an anonymous function without the extra parentheses, though its capabilities with respect to argument-passing are a bit limited at the moment. I ve raised a proposal to broaden them.

Currently, the equivalent of your code example would be

do ->
  $ = jQuery
  ...

If my proposal is accepted, it will be possible to write

do ($ = jQuery) ->
  ...

instead.

Answer 3

Short variant

do ($=jQuery)->
 app = $.sammy ->
   @get  #/ , -> $("#main").text   
   @get  #/test , -> $( #main ).text  Hello world 
 $ -> app.run()

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