Execution order of if else issue

I have function, a part of it works non-correct.

What i need -

1) if window width < 768 (do smth) 2) if window width = 768 (do smth) 3) else (do smth)

There is a part of function

var windowWid = $(window).width();
if ($poselok.length > 0) {
    if (windowWid === 768) {
        var offset = 0.05;
    }
    if (windowWid < 768) {
        var offset = 0 - $el_full.offset().left - el_margin_left;
    } else {
        var offset = 0 - $el_full.offset().left + $sideLeft + 15;
    }
} else {
    var offset = 0 - $el_full.offset().left - el_margin_left;
};

Without if (windowWid < 768) condition if (windowWid === 768) works, but with it - doesn't.

I tried if (windowWid < 767) and if (windowWid <= 767) to separate if but nothing.

I tried replace if, (windowWid === 768) works but if (windowWid < 768) works incorrect.

I think i have mistake in Execution order, but don't know how to fix it.

Help please!