jquery mouseleave also firing during enter

jquery mouseleave also firing during enter

I have a simple jquery code :

 $(document).ready(function(){ 
var
i=0;
$
(this).mouseleave(function(){
$
('body').append(++i+'<br/>');
});
});

This code is firing even when the mouse enters the browser window. How do I make it fire only when the mouse leaves the browser window ? This is a problem in chrome for me.

Working example here :  http://tapasdwivedi.com/test1/