鼠标滚轮向上出现header导航，滚轮向下隐藏header

找了个简单的实现，之前是看yahoo这么做的，觉得很不错，用户体验好一点

<script>
var agent = navigator.userAgent;
if (/.*Firefox.*/.test(agent)) {
document.addEventListener("DOMMouseScroll", function(e) {
e = e || window.event;
var detail = e.detail;
if (detail > 0) {
$("#header").css('display','none');
$("#content-box").css('padding-top','0px')
console.log("鼠标向下滚动");
} else {
$("#header").css('display','block');
$("#content-box").css('padding-top','82px')
console.warn("鼠标向上滚动");
}
});
} else {
document.onmousewheel = function(e) {
e = e || window.event;
var wheelDelta = e.wheelDelta;
if (wheelDelta > 0) {
$("#header").css('display','block');
$("#content-box").css('padding-top','82px')
console.log("鼠标向上滚动");
} else {
$("#header").css('display','none');
$("#content-box").css('padding-top','0px')
console.warn("鼠标向下滚动");
}
}
}
</script>