gotoByScroll

gotoByScroll.js

/**
Smooth scroll to element

gotoByScroll({
    target: $(targetID),
    speed: 700,
    vOffset: 0,
    easing: "easeInOutQuad",
    onStart: function (trg) {
        // your function...
    },
    onEnd: function (trg) {
        // your function...
    }
});

*/

function gotoByScroll(s) {

    if (!s || !s.target) {
        return false;
    }

    var topOffset = (s.target && s.target.length) ? parseInt(s.target.offset().top) : 0,
        speed = ((s.speed && !isNaN(s.speed)) || s.speed === 0) ? parseInt(s.speed) : 500,
        easing = (s.easing && $.easing.hasOwnProperty(s.easing)) ? s.easing : "swing",
        enableOnStartinPosition = s.enableOnStartinPosition || false,
        enableOnEndinPosition = s.enableOnEndinPosition || false,
        vOffset = (s.vOffset && !isNaN(s.vOffset)) ? parseInt(s.vOffset) : 0,
        onStart = (s.onStart && typeof s.onStart === "function") ? s.onStart : null,
        onEnd = (s.onEnd && typeof s.onEnd === "function") ? s.onEnd : null,
        documentObj = (window.webkitURL) ? "body" : "html",
        inPosition = false;

    topOffset = Math.floor(topOffset);

    // check if object is already in position
    if (s.target && s.target.length) {
        if (topOffset + vOffset === $(document).scrollTop()) {
            speed = 0;
            inPosition = true;
        }
    }

    // start callback
    if (onStart) {
        if (!inPosition || (inPosition && enableOnStartinPosition)) {
            // do not proceed if callback returns false
            if (onStart(s.target, speed, topOffset, vOffset) === false) {
                return false;
            }
        }
    }

    $(documentObj).stop(true).animate({scrollTop: topOffset + vOffset}, speed, easing, function () {
        // end callback
        if (onEnd) {
            if (!inPosition || (inPosition && enableOnEndinPosition)) {
                onEnd(s.target, speed, topOffset, vOffset);
            }
        }
        return this;
    });
}