jquery和css3如何实现航栏到底部上移（代码）

.navigation {
 position: fixed;
 bottom: 100px;
 right: 100px;
 z-index: 100;
}.navigation {
 transition: bottom 2s;
 -webkit-transition: bottom 2s;
}

var nav = eval($('.navigation').offset().top - $(window).scrollTop());
$(window).on('scroll', function() {
 var navh = $('.navigation').height();
 var foot = parseInt($('.footer').offset().top - $(this).scrollTop() - navh);
 /*console.log(nav - foot);*/
 if(nav == foot || nav > foot) {
 $('.navigation').css({
 'position': 'fixed',
 'bottom': '400px'
 });
 } else {
 $('.navigation').css({
 'position': 'fixed',
 'bottom': '100px'
 });
 }
});