Consider:

```
function fibo() {
    var first, second, add;
    for(var i=0; i<4000; i++) {
        if(i === 0) {
            first = 1;
            second = 2;
        }
        add = first + second;
        first = second;
        second = add;
    }
    alert(add);
}

fibo();

```

It is not working and shows infinity. Why?