Pattern for CoffeeScript modules [duplicate]

Answer 1

The good thing about this approach is that it creates private variables, so there won't be any conflict with variable names:

(function() {
  var privateVar = 'test';
  alert(privateVar); // test
})();

alert(typeof privateVar); // undefined

The addition of .call(this) makes the this keyword refer to the same value as it referred to outside the function. If it is not added, the this keyword will automatically refer to the global object.

A small example to show the difference follows:

function coffee(){
  this.val = 'test';
  this.module = (function(){
    return this.val;
  }).call(this);
}

var instance = new coffee();
alert(instance.module); // test

function coffee(){
  this.val = 'test';
  this.module = (function(){
    return this.val;
  })();
}

var instance = new coffee();
alert(typeof instance.module); // undefined