A simple javascript/coffeescript helper function to run different callbacks for different number of arguments

variableArgs.js

var variableArgs,
  slice = [].slice;

variableArgs = function(callbacks) {
  var defaultKey;
  defaultKey = 'default';
  return function() {
    var args, numArgs, ref;
    args = 1 <= arguments.length ? slice.call(arguments, 0) : [];
    numArgs = args.length || 0;
    return ((ref = callbacks[numArgs]) != null ? ref : callbacks[defaultKey]).apply(null, args);
  };
};

variableArgs.coffee

variableArgs = (callbacks) ->
	defaultKey = 'default'
	(args...) ->
		numArgs = args.length or 0
		(callbacks[numArgs] ? callbacks[defaultKey])(args...)

example.js

var exampleFn = variableArgs({
	'1': function(arg) {
		// Return the reverse of the argument
		return String(arg).split("").reverse().join("");
	},
	'2': function(arg1, arg2) {
		// Return the strings combined with a space in the middle
		return String(arg1) + " " + String(arg2);
	},
	'3': function(arg1, arg2, arg3) {
		// Return the strings combined with the third in the middle
		return String(arg1) + String(arg3) + String(arg2);
	},
	'default': function() {
		return String();
	}
});

exampleFn("reverse me!");
// => "!em esrever"

exampleFn("arg1", "arg2");
// => "arg1 arg2"

exampleFn("arg1", "arg2", ", ");
// => "arg1, arg2"

exampleFn();
// => ""

exampleFn("too", "many", "arguments", "will", "spoil", "the", "broth");
// => ""