jQuery plugin to set scroll followable items i.e. they follow the scroll but from one point to another they take fixed position.

follow.js

$.fn.follow = function (from, to, offset, fixedOptions) {
    var $this = this,
        $window = $(window);

    offset = offset || 0;

    fixedOptions = fixedOptions || {};

    from_y = from || 0;   
    to_y = to || Number.MAX_VALUE;

    $window.scroll(function (e) {
        if (isNaN(from)){
          from_y = $(from).offset().top
        }
        if (isNaN(to)){
          to_y = $(to).offset().top - parseInt($(to).css('margin-top')) - parseInt($(to).css('padding-top')) - $this.outerHeight() - offset;
        }
        if ($window.scrollTop() < from_y){
            $this.css({
                position: 'relative',
                top: 0,
            });
        }else if ($window.scrollTop() >= from_y && $window.scrollTop() <= to_y) {
            $this.css({
                position: 'fixed',
                top: offset,
            });
            $this.css(fixedOptions);
        } else if ($window.scrollTop() > to_y){
            $this.css({
                position: 'relative',
                top: to_y - from_y,
            });
        }
    });
};