Once function in JS

once.coffee

once = (func) ->
  calls = 0
  ->
    calls+=1
    if (calls > 1)
      throw "baad girl"
    func.apply(this, arguments)

m = once -> alert "hello"

m()
m()

once.js

var m, once;
once = function(func) {
  var calls;
  calls = 0;
  return function() {
    calls += 1;
    if (calls > 1) {
      throw "baad girl";
    }
    return func.apply(this, arguments);
  };
};
m = once(function() {
  return alert("hello");
});
m();
m();