[рони]

snovapavel,
ошибки не существенные, могли бы сами точки с запятыми добавить или можно не обращать внимания.

$(function() {
    var duration = 2000,
        play = false;

    function swingFromTo(a) {
        var b = 1.70158;
        return (a /= 0.5) < 1 ? 0.5 * a * a * (((b *= 1.525) + 1) * a - b) : 0.5 * ((a -= 2) * a * (((b *= 1.525) + 1) * a + b) + 2);
    }
    $("a[href*=#]:not([href=#])").click(function() {
        if (location.pathname.replace(/^\//, "") == this.pathname.replace(/^\//, "") && location.hostname == this.hostname) {
            var target = $(this.hash);
            target = target.length ? target : $("[name=" + this.hash.slice(1) + "]");
            if (target.length) {
                if (play) return;
                play = true;
                var d = performance.now();
                var from = window.pageYOffset;
                var to =
                    target.offset().top;
                window.requestAnimationFrame(function foo(a) {
                    a = (a - d) / duration;
                    if(1 < a) a = 1;
                    var progress = swingFromTo(a);
                    window.scrollTo(0, from - (from - to) * progress);
                    if (a == 1) play = false;
                    else window.requestAnimationFrame(foo);
                });
                return false;
            }
        }
    });
});