var obj = {
      yes: function(){
          // this == obj
          this.val = true;
      },
      no: function(){
          this.val = false;
      }
  };
  
  // We see that there is no val property in the 'obj' object
  alert( obj.val == null );
  
  // We run the yes function and it changes the val property
  // associated with the 'obj' object
  obj.yes();
  alert( obj.val == true );
  
  // However, we now point window.no to the obj.no method and run it
  window.no = obj.no;
  window.no();
  
  // This results in the obj object staying the same (as the context was
  // switched to the window object)
  alert( obj.val == true );
  
  // and window val property getting updated.
  alert( window.val == false );