function something()
{

	var x = window.localStorage.getItem('aaa');

	x = x * 1 + 1;

	window.localStorage.setItem('aaa', x);

	alert(x);
}

function add_to_cart(id)
{
	alert('You added pizza with id: ' + id)
}
//function something()
//{
//	var x = window.localStorage.getItem('aaa');
//	x = x * 1 + 1;
//	window.localStorage.setItem('aaa', x);
//	alert(x);
//}

function add_to_cart(id)
{
	var x = window.localStorage.getItem('product_' + id);
	x = x * 1 + 1;
	window.localStorage.setItem('product_' + id, x);
}
add product js