Handling fixed position in relation to touch devices - scroll

Question

The menu is fixed and will follow on scroll. This does not work well with touch devices.
I want to call the script, using Modernizr, when it detect no-touch devises. But I'm unsure how to do this.
Also, is there elements from the Modernizr download-page that I need to accomplish this?
Here is my script:
$(document).ready(function() {
$(window).scroll(function() {
var header = $('#fixed-bar').outerHeight(true);
console.log(header);
var scrollTopVal = $(this).scrollTop();
if ( scrollTopVal > header ) {
$('nav').css({'position':'fixed','top' :'0px', 'border-bottom':'4px solid #ff5454'});
} else {
$('nav').css({'position':'absolute','top':'90px', 'border-bottom':'none'});
}
});
});

Answer 1

But I'm unsure how to do this.
You don't want to just use javascript, you want to use mostly css, and just toggle classes with javascript. Its more performant (which is super important with something like scroll loops).
#fixed-bar {
position: fixed;
top: 0px;
border-bottom:4px solid #ff5454;
}
.touch #fixed-bar, #fixed-bar.at-top {
top: 90px;
border-bottom: none
}
also, you don't want to directly attach to window.scroll. Instead, you want to use requestAnimationFrame (shimming where needed) to get the most buttery smooth animations possible. Here is a coffeescript example for jQUery.With that, you would be looking to do something like this
$(document).ready(function() {
// the height doesn't change, so we don't need to look it up on scroll.
var headerHeight = $('#fixed-bar').outerHeight(true);
$.request_scroll(function() {
var scrollTopVal = $(this).scrollTop();
if ( scrollTopVal > headerHeight ) {
$('nav').addClass('at-top');
}
else {
$('nav').removeClass('at-top');
}
});
Also, is there elements from the Modernizr download-page that I need to accomplish this?
just the Modernizr.touch test.
Be warned, this doesn't detect touch screens, just devices that support touchevents. That means new windows 8 laptops will be detected as .touch, and windows phones will not (they use pointer-events, not touch events).

Answer 2

I now have a fiddle with help from Patricks answers, but as you can see, the bar does still not go to the top, when you scroll as it should, like on my website.
Is there a solution for this? Tablets and phones don't like effects, which have $(window).scroll(function().
Currently I have this javascript on my website (the id's are different):
$(document).ready(function() {
$(window).scroll(function() {
var header = $('#fixed-bar').outerHeight(true);
console.log(header);
//this will calculate header's full height, with borders, margins, paddings
var scrollTopVal = $(this).scrollTop();
if ( scrollTopVal > header ) {
$('nav').css({'position':'fixed','top' :'0px', 'border-bottom':'4px solid #ff5454'});
} else {
$('nav').css({'position':'absolute','top':'90px', 'border-bottom':'none'});
}
});
});
While most tablets have problems with $(window).scroll(function(), it works on desktop pc. Not much consolation though.
Is there an alternate way of getting this to work? Using touch- and pointer events, maybe someone has a working fiddle og example?