Checking the value of a variable inside unslider.js

i have a question about a plugin that i have been trying to debug for sometime . it a simple carousel plugin . heres what i wanna know.

there is this function ,

_this.play = function() {
            // console.log('Inside _play function');
            _this.t = setInterval(function() {
                // console.log(_this.i);
                _this.to(_this.i + 1);  
            }, _this.o.delay | 0);
        };

the first time the above function executes it calls another function caled _this.to(_this.i + 1) , notice how it calls the function with a parameter _this.i .

_this.i is basically the following :

_this.i = 0; 

now as soon as the _this.to function is called , the following happens :

_this.to = function (){


// alot of code , but that's irrelevant

 _this.i = index;

}

ok so heres my difficulty and heres my question :

So the first time _this.play() calls _this.to() , _this.i = 0 , then _this.i enters _this.to() and now _this.i = index ?? Am i right . that would be my first question .

consider _this.play() is gonna call _this.to() more than once , lets say 3 time , does that mean , _this.i = 0 only the 1st time _this.to() is called and then on _this.i = index ?? so say the second time we say :

_this.play = function() {
            _this.t = setInterval(function() {
                _this.to(_this.i + 1);
            }, _this.o.delay | 0);
        };  

What we are really saying on line 3 of the above function is

_this.to(index + 1)

?

am i right ?

I know its a twisted question , but i'am sure someone on here can answer it .

Thank you.

Alexander.