scope and closure

<script>

var i;

var resetI = function()

{

   i = 1;

};

function Counter(){

this.i = window["i"] + 10;

   return {

      inc: function(){++i;},

      dec: function(){i--;},

      value: function(){return i;}

   };

};

function Counter2(){

    this.i = window["i"] + 10;

    this.inc = function(){++i;};

    this.dec = function(){--i;};

    this.value = function(){return i;};

}

function Counter3(){

    this.i = window["i"] + 10;

   return function(i){

      return{

      inc: function(){++i;},

      dec: function(){i--;},

      value: function(){return i;}

      }

  }(this.i);

}

resetI();

var one = new Counter();

one.inc();

one.inc();

one.dec();

alert(one.value());//2

var two = Counter();

two.inc();

alert(one.value());//13

alert(two.value());//13

resetI();

var three = new Counter2();

three.inc();

three.inc();

three.dec();

alert(three.value());//2

var four = Counter2();

//four.inc();  //complain undefined

inc();

alert(three.value());//13

//alert(four.value());  //complain undefined

alert(value());//13

resetI();

var five = new Counter3();

five.inc();

five.inc();

five.dec();

alert(five.value());//12

var six = Counter3();

six.inc();

six.inc();

six.inc();

alert(five.value());//12

alert(six.value());//14

resetI();

</script>