Angular modules are wrapped around function(window, angular, undefined) even when they do not need to

Question

I noticed that modules in angular are wrapped by a function with the same definition:

(function(window, angular, undefined){
     .....
})(window, window.angular);

even they do not use it. For example angular cookies has that but window is never used. Why is this? I understand they closure principle, to remove variables from the global scope, but this does not explain all of it.

Thanks, Vlad

Answer 1

This is to ensures the meaning of these variables do not get changed by something else.

for example:

window.angular = "333";


(function test() {
  var angular = "111"; //changing the meaning of angular
  var undefined = 222;  //changing undefined to 222
  (function iife() {
    document.write('Not Passed in: <br/>');
    document.write('angular == ' + angular);
    document.write('<br/>')
    document.write('undefined == ' + undefined);
    document.write('<br/>')
    document.write('<br/>')
  })();
  
  
  (function iife(angular,undefined) {

    document.write('Passed in: <br/>');
    document.write('angular == ' + angular);
    document.write('<br/>')
    document.write('undefined == ' + undefined);
    document.write('<br/>')
    document.write('<br/>')
  })(window.angular, window.undefined);
  
})();