页面滚动固定

实例代码：

$(document).scroll(function () {

        var $leftBox = $('.lFixedBlock'),
                $rightBox = $('.rFixedBlock'),
                leftBoxHeight = $leftBox.height(),
                rightBoxHeight = $rightBox.height(),
                windowHeight = $(window).height(),
                scrollTop = $(document).scrollTop(),
                diffHeight = leftBoxHeight - rightBoxHeight;
        if (diffHeight > 0) {
            if ((scrollTop + windowHeight) > (leftBoxHeight + $leftBox.offset().top)) {
                $rightBox.css({'position': 'fixed', 'bottom': (scrollTop + windowHeight) - (leftBoxHeight + $leftBox.offset().top)});
            } else if ((scrollTop + windowHeight) > (rightBoxHeight + $leftBox.offset().top)) {
                $rightBox.css({'position': 'fixed', 'bottom': 0});
            } else {
                $rightBox.css({'position': 'static', 'bottom': 'auto'});
            }
        } else {
            if ((scrollTop + windowHeight) > (rightBoxHeight + $rightBox.offset().top)) {
                $leftBox.css({'position': 'fixed', 'bottom': (scrollTop + windowHeight) - (rightBoxHeight + $rightBox.offset().top)});
            } else if ((scrollTop + windowHeight) > (leftBoxHeight + $rightBox.offset().top)) {
                $leftBox.css({'position': 'fixed', 'bottom': 0});
            } else {
                $leftBox.css({'position': 'static', 'bottom': 'auto'});
            }
        }

    });