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Hide Menu on scroll down (but only after 50px)

This script makes it so when you scroll down in a browser the navigation bar disappears/hides behind the header. I was wondering if it was possible if instead it hid as soon as you scrolled down, hiding it after a user scrolls down a certain number of pixels (say 50px) to avoid touchy nav hiding on slightest scroll.
Thanks in advance for any direction.
// Nav scroll test
var prev = 0;
var $window = $(window);
var nav = $('#belowhead');
$window.on('scroll', function(){
var scrollTop = $window.scrollTop();
nav.toggleClass('hidden', scrollTop > prev);
prev = scrollTop;
});

You can put this inside your "window.on('scroll')" function:
if(scrollTop > 50) {
nav.addClass('hidden');
} else {
nav.removeClass('hidden');
}

2019 Update / Adjustment
The following could be useful for anyone else wishing to develop a header that disappears when you scroll down. I just finished making the following for a website I'm creating that required the top header to disappear when the user started scrolling, but then reappear when they start scrolling up; continuously applying this logic if you were to constantly keep scrolling up and down on the website.
For starters, a class is added to my header tag called nav-scrolled when the user scrolls past a certain point - 50px in this case. This new class can then be styled to change the background-color, add a box-shadow etc...
$(function() {
var header = $(".nav-container");
$(window).scroll(function() {
var scroll = $(window).scrollTop();
if (scroll >= 50) {
header.addClass("nav-scrolled");
} else {
header.removeClass("nav-scrolled");
}
})
});
However, this only solved the problem of not being able to edit the headers styles if the user is scrolling from the top of the page - not anywhere on the site - the following fixes this.
var userScroll;
var scrollTop = 0;
var delta = 5;
var navHeight = $('header').outerHeight();
$(window).scroll(function(event){
userScroll = true;
});
setInterval(function() {
if (userScroll) {
hasScrolled();
userScroll = false;
}
}, 250);
The next step for me was to sequentially add and remove classes show-nav and hide-nav that had been styled to display and hide the navigation menu. The following checks whether the user has scrolled (up or down) to a value higher than my delta variable. If the user is beginning to scroll up on the website, the class show-nav is added and the header transitions in from the top of the page. If the user is scrolling down the page the class hide-nav is added, and the header is hidden.
function hasScrolled() {
var st = $(this).scrollTop();
// Ensures a higher scroll than $delta
if(Math.abs(scrollTop - st) <= delta)
return;
// If they scrolled down and are past the navbar, add class .nav-up.
// This is necessary so you never see what is "behind" the navbar.
if (st > scrollTop && st > navHeight){
// Scroll Down
$('header').removeClass('show-nav').addClass('hide-nav');
$('.nav-toggle').removeClass('open');
$('.menu-left').removeClass('collapse');
} else {
// Scroll Up
if(st + $(window).height() < $(document).height()) {
$('header').removeClass('hide-nav').addClass('show-nav');
}
}
scrollTop = st;
}

Add Class only on browser Scroll Up

Is there any way to add class to an element only when someone scrolls the browser page up?
Problem Filide>>
JS
$(window).scroll(function() {
var scroll = $(window).scrollTop();
if (scroll <= 100) {
$(".nav").addClass("darkHeader");
} else {
$(".nav").removeClass("darkHeader");
}
});
Problem is this js add class when scroll-down page. But I want to add class when Scroll Up browser and after that when scroll down class will remove. See Example demo>>

If you want to know whether the user has scrolled up or down you need to track of the last scroll position. Then check if the new scroll position is greater or less than that position. You can then set the classes accordingly
// Script
lastScroll = 0;
$(window).on('scroll',function() {
var scroll = $(window).scrollTop();
if(lastScroll - scroll > 0) {
$(".nav").addClass("darkHeader");
} else {
$(".nav").removeClass("darkHeader");
}
lastScroll = scroll;
});
JSFiddle

fixed menu that is fixed after scrolling past a div

I am creating a fixed position sub-nav menu bar for a responsive site. All the examples I can find of a fixed menu that sticks to top after scrolling are based on a set number of pixels from top.
However, since I am working a responsive site the pixels from top where I need the menu to come in are different based on viewport (on small screens, the menu should appear after more area scrolled down because the content fills are taller area of screen).
I have a working example and am using the following jquery script:
$(document).ready(function(){
$('#navigation a, #fixedbar a').on('click', function(e) {
e.preventDefault();
});
$(window).on('scroll',function() {
var scrolltop = $(this).scrollTop();
if(scrolltop >= 215) {
$('#fixedbar').fadeIn(250);
}
else if(scrolltop <= 210) {
$('#fixedbar').fadeOut(250);
}
});
});
As you can see the fixed bar fades in if more than 215 pixels scrolled from the top. Instead I'd like to have it appear after scrolling past a certain div. That way I know it will come in after user has fully scrolled past the intro text.
Here's my fiddle
Any good examples out there of what I want to do? Or easy way to modify the jquery script? Thanks in advance.

This modification will make it fade in after it passes the static nav
DEMO
var $nav = $("#navigation");
if(scrolltop >= $nav.offset().top + $nav.height()) {
$('#fixedbar').fadeIn(250);
}
else {
$('#fixedbar').fadeOut(250);
}

Demo http://jsfiddle.net/EHhQE/1/
You need to fade out and fade in the navigation when the scroll reaches the bottom and the top of the navigation bar respectively.
var topOfDiv = $('#navigation').position().top;
var bottomOfDiv = $('#navigation').position().top+$('#navigation').outerHeight(true);
And fetched in your code:
$(document).ready(function(){
$('#navigation a, #fixedbar a').on('click', function(e) {
e.preventDefault();
});
$(window).on('scroll',function() {
var scrolltop = $(this).scrollTop();
var topOfDiv = $('#navigation').position().top;
var bottomOfDiv = $('#navigation').position().top+$('#navigation').outerHeight(true);
if(scrolltop >= bottomOfDiv) {
$('#fixedbar').fadeIn(250);
}
else if(scrolltop <= topOfDiv) {
$('#fixedbar').fadeOut(250);
}
});
});

$(document).ready(function ()
{
slider();
});
$(window).scroll(function ()
{
slider();
});
function slider()
{
if (document.body.scrollTop > 208)
$('#fixedMenu').fadeIn(0);
else
$('#fixedMenu').fadeOut(0);
}

Menu bar fixed at top of the page when scrolling is causing content underneath to jump during scroll

I'm trying to have a submenu stay at the top of the page while scrolling once it reaches the top during scrolling. Here is what I have so far:
$(window).scroll(function () {
if ($(window).scrollTop() > 175) {
$('#location_menu').css('position', 'fixed').css('top','0px').css('z-index','1000');
$('.first').css('padding-top','415');}
else {
$('#location_menu').css('position', 'relative').css('z-index','1');
}});
The issue I'm having is that the scroll is not smooth and once the element changes from position:relative to position:fixed the content seems to jump/skip up about 415px which is the same height as the submenu.
Here is the css:
<div id="location_menu" >submenu content
</div>
<div id="content" class="location_detail first">content beneath submenu
</div>
I've added the line for .first to have a padding-top of 415px when the page is crolling and reaches within 175px of the top of the page .css('padding-top','415') this doesn't actually seem to be doing anything though. There is no change, so I assume I have executed it incorrectly.
Should I use a different scrolling function then I have listed above?
Here is what I ended up using to fix my problem, based off the code from #Danko :
$(window).scroll(function () {
var $conten = $('.first'),
$menu = $('#location_menu')
scrollpos = $(window).scrollTop();
if (scrollpos >= 175) {
$conten.css('padding-top','365px');
$menu.css('position', 'fixed').css('top','0px').css('z-index','1000');
} else {
$conten.css('padding-top','0');
$menu.css('position', 'fixed').css('position', 'relative').css('z-index','1');
}
});

Edit
Ok now that i understand the question, i did this demo http://codepen.io/anon/pen/BdkLf.
The function in fact is this:
$(window).scroll(function () {
var $menu = $('#location_menu'),
$conten = $('#content'),
scrollpos = $(window).scrollTop();
if (scrollpos >= 175) {
$menu.css( {
"top" : "0",
"position": "fixed",
});
$conten.css('top','375px' );
} else {
$menu.css( {
"position": "relative",
"top" : "175px",
});
$conten.css('top','175px');
}
});
Here 175 is equals to the initial distance from the top and 375 is the addition between the distance and the height of your menu

Fade in header when adding and removing classes with jQuery

I'm designing a nav that has the background bar appear after the user has scrolled down the page a bit. When they scroll back to the top, the bar (background color) disappears. I'm doing it using the instructions over at:
Add/remove class with jquery based on vertical scroll?
It works fine but now I would like to add fading in and out of the bar on scroll. I've tried adding the fadeIn() and fadeOut() methods. Problem is when it fades out, it fades out the whole #nav div! Not just the background colour. Here's the query
$(function() {
//caches a jQuery object containing the header element
var header = $('.noBackground');
$(window).scroll(function() {
var scroll = $(window).scrollTop();
if (scroll >= 500) {
header.removeClass('noBackground').addClass('blackBackground').fadeIn();
} else {
header.removeClass('blackBackground').fadeOut().addClass('noBackground');
}
});
});
Full, HTML, CSS and jQuery on this fiddle

The problem here is your #nav div is hidden when you scroll back to top. It is because the .fadeOut() method hides the matched elements by fading them to transparent. So you you remove .fadeOut() from else condition and it works fine.
Here is the edited code.
$(function() {
//caches a jQuery object containing the header element
var header = $('.noBackground');
$(window).scroll(function() {
var scroll = $(window).scrollTop();
if (scroll >= 500) {
header.removeClass('noBackground').addClass('blackBackground').fadeIn();
} else {
header.removeClass('blackBackground').addClass('noBackground');
}
});
});
Edit:
A simple twist will show the effect:
$(function() {
//caches a jQuery object containing the header element
var header = $('.noBackground');
$(window).scroll(function() {
var scroll = $(window).scrollTop();
if (scroll >= 500) {
if(header.hasClass('noBackground')) {
header.hide();
header.removeClass('noBackground')
.addClass('blackBackground').fadeIn(2000);
}
} else {
if(header.hasClass('blackBackground')) {
header.hide();
header.removeClass('blackBackground')
.addClass('noBackground').fadeIn(2000);
}
}
});
});
Demo Fiddle.

fadeOut() method can be implemented on a jquery element,not on a class..your code is working perfectly fine