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Navigation bar doesn't work with Intersection Observer API

I have a problem when I use the Intersection Observer API. I am trying to use it for, once the nav-bar is not visible anymore when you scroll, make this latter appears with a white background and fixed to the viewport.
I first of all tried to console.log('visible') and console.log('visible') when the nav-bar is visible or not and I succeed ! But when I wanted to apply the new class when the navbar wasn't visible anymore, my page starting to get mad : the class was applied and removed, and the console was only displaying "visible", "not visible" all the time very frequently.
I think it is because when I apply the class, it moves the rootMargin (of the options object) but I don't know how to fix it.
My entire website (my code is in app.js) : https://replit.com/#Xeway/IntersectionObserver#app.js
PS : I only have build app.js, HTML and CSS are codes made by FreeCodeCamp.
PS : Sorry for the link, but I can't share this code here because my code uses backtick and it doesn't seems to work ^^ Also, try to open the website with a big width because it's responsive and you can see more precisely the problem when it's on a computer's screen width.
Thank you in advance for your answers guys :)

Intersection observer is not needed for your case.
You just need to apply class to your header, when window is scrolled beyond certain height.
In your case, it would be equal to the height of the header.
So, when the window scroll height > height of the header, then apply class
and in the else, remove the class.
Call the same function on document.ready as well (To check the window scroll position on the page load, if the window is already scrolled).
Here is the little script for your help:
$(window).scroll(function() {
var scroll = $(window).scrollTop();
// assume 100px is the height of the header
if (scroll >= 100) {
addScrolledClassToHeader();
} else {
removeScrolledClassToHeader();
}
});
function addScrolledClassToHeader() {
$('header.site-header').addClass('header-is-scrolled');
}
function removeScrolledClassToHeader() {
$('header.site-header').removeClass('header-is-scrolled');
}

Javascript Div Scroll - Some Issues

I copied this from another post, not blindly, I can see what it does but I can't think of a way to fix the problem. I am not really proficient in JavaScript but I can read this snippet.
// The function actually applying the offset
function offsetAnchor() {
if (location.hash.length !== 0) {
window.scrollTo(window.scrollX, window.scrollY - 100);
}
}
// This will capture hash changes while on the page
$(window).on("hashchange", function() {
offsetAnchor();
});
// This is here so that when you enter the page with a hash,
// it can provide the offset in that case too. Having a timeout
// seems necessary to allow the browser to jump to the anchor first.
window.setTimeout(function() {
offsetAnchor();
}, 3);
;(function($) {
$('.swipebox').swipebox();
})(jQuery);
The issue was, that when I was scrolling to DIVs with ID's used for anchor points, I was scrolling slightly too far down as I have a sticky header. I tried using this so when changing DIV it would account for the sticky header, it doesn't exactly work perfectly but the main issue I am having, is that I will have over 12 navigation DIV ids, and every time anyone of them is clicked it no longer goes to the DIV, but instead just scrolls up -100 pixels.
I essentially need a solution that will scroll to just above where I need it without affecting the rest of my menu functionality, it doesn't have to be achieved by JS but that's the only feasible way I can see a solution (I've tried thinking of a CSS only one but margin/padding won't help in this situation of scrolling)
To give one last detail, when clicking on a navigation div it will scroll to that div, and the menu (sticky header) will cover some of the image and the of the item scrolled too. Major problem :)
I can leave a link if you'd like a better description and I am learning JS at the moment, but as this is for a client I'd love to be able to fix it within a timely manner and would greatly appreciate any and all help anyone can offer.
Thank you.

In this question there's an answer for jumping to certain element.
If you want a smooth scroll: look here.

Scrolling layout - like facebook or google plus right sidebar

Any idea how make a layout like google plus or facebook. You can see at google plus home as example,
at the beginning, if you scroll the page in the main content, they will scroll together (friend post and sidebar), but when you scroll until the bottom of sidebar (in the right of friend post), that sidebar will stop scrolling , but the another content (friend post) will still scrolling. can explain to me how to make layout like that? sample code or demo will be very help.

Fixed positioning with CSS is a very limited approach. There are a number of ways to do this style of "fixed" areas, many of which have already been given in answers to similar questions on here (try the search above?).
One technique (which many are based on) is like so (in brief)..
Capture the browser's scrolling
Get the position from top of chosen element (x)
Check if the scrolling > x, if so apply a class to the element to fix it to a certain position.
The same will work in reverse, for example:
var target = $('#div-to-stick');
var div_position = target.offset().top;
$(window).scroll(function() {
var y_position = $(window).scrollTop();
if(y_position > div_position) {
target.addClass('fixed');
}
else {
target.removeClass('fixed');
}
}
Note: Depending on how you chose to complete the code above, the page will often "jump" as the div's position is modified. This is not always a (noticeable) problem, but you can consider getting around this by using .before with target.height() and appending a "fake" replacement div with the same height.
Hope this helps.

The new approach with css3 is reduce your effort. use single property to get it.
position:sticky;
here is a article explained it and demo.
article
Demo

You are looking for CSS position:fixed (for the scroll-along sidebar), you can set the location with left:[length], right:[length], top:[length], bottom:[length] and the normal width and height combos
You will need to augment it with a window resize and scroll listener that applies the position:fixed property after the window has scrolled past the top of the sidebar.

Use css property (position:fixed). This will keep the position of the div fixed even if you scroll down or scroll up.

iscroll issue with two dimensional ( horizontal + vertical ) scrolling, scrollable are related issue?

Problem in brief
I have got a piece of working two dimensional scrolling code. Scrolling as such is working fine. Scrolling can be done in any direction (not like restricted to only horizontal or only vertical at a ti,e) but there are two problems -
Scrolling beyond the visible area towards top and left, does not bounce back the scrollable area.
Scrolling to right and bottom bounces back.
Problem demo - http://jsfiddle.net/sandeepan_nits/pAhjU/6/
Note - Test in webkit browsers only (Google chrome and Safari).
Solution I am looking for
Either, point out what is wrong in my code.
Or share any properly implemented working demo of both ways scroll (horizontal + vertical) using the same version of iscroll, so that I can follow the same. I am using - version 3.7.1, preferable, or using iscroll version 4, fine as well.
Or any pointers, of course, would be appreciated.
Problem Description
Please check working code here - http://jsfiddle.net/sandeepan_nits/pAhjU/6/
Note -
Test in webkit browsers only (Google chrome and Safari).
I have knowingly put everything inside the HTML section in the jsfiddle, because if I separate things completely, the scrolling does not work, and I am not sure where exactly it stops working. Thanks if you can point out.
Code
Here is the HTML -
<div class="header">
<div class='left_link'></div>Demo</div>
<div id="main_content" class="main_content">
<b><div id=scroller1><br/>
<div class='center_data'>Scrollable area</div>
<div class='center_data'>hello world!</div>
<br/>
</div></b>
</div>
Note - I know there is invalid html there - <div id=scroller1> is inside <b></b> and I am not sure why if I remove the <b></b> tags, horizontal scrolling does not work anymore - check here.
Here is the js -
var myScroll;
var a = 0;
function loaded() {
//setHeight(); // Set the wrapper height. Not strictly needed, see setHeight() function below.
// Please note that the following is the only line needed by iScroll to work. Everything else here is to make this demo fancier.
myScroll = new iScroll('scroller1', {desktopCompatibility:true});
//myScroll2 = new iScroll('scroller2', {desktopCompatibility:true});
}
// Prevent the whole screen to scroll when dragging elements outside of the scroller (ie:header/footer).
// If you want to use iScroll in a portion of the screen and still be able to use the native scrolling, do *not* preventDefault on touchmove.
document.addEventListener('touchmove', function (e) { e.preventDefault(); }, false);
// Load iScroll when DOM content is ready.
document.addEventListener('DOMContentLoaded', loaded, false);
I guess the reason is that the scrollable div is by default rendered at the bottom-right corner of the scrollable area. But I am not sure about the proper way to configure those things - how to set where to render the scrollable div inside the scollable area. So far I did not find any working demo of both ways scrolling - horizontal + vertical scrolling.
I checked out the documentation of iscroll and many working demos, but did not find any demo where scrolling can be done both ways - horizontally as well as vertically. I checked the "Accepted options are:" section under "Syntax" section in http://cubiq.org/iscroll but none of those params seem to be what I am exactly looking for.
Other things
Also, one more thing, I am not able to view the area covered by dom elements in chrome browser, while I inspect the given scroll demo. By viewing the area I mean moving the mouse over the dom inspector panel highlights the dom in the browser view. When does it not appear? I checked with validated HTML as in http://jsfiddle.net/sandeepan_nits/pAhjU/12/.
Somebody please create a tag iscroll or iscroll3 so that I can retag my question.
Update
I just want to have normal two dimensional scrolling with the scroll area being properly inside the visible screen and there should be bounce back on taking outside the screen. Right now there is no bounce back (in my jsfiddle) on scrolling towards top and left, outside screen. Bounce back happens on scrolling to right and bottom. I just want the scrolling area to be well placed inside the screen. I guess bounce back will automatically get fixed then.

I think the last version (4.1.8) on the github repo will fix your problem ;) I'm using it on some projects and it is now optimized for desktop browser ;)
Edit
From the documentation :
hScroll, used to disable the horizontal scrolling no matter what. By default you can pan both horizontally and vertically, by setting this parameter to false you may prevent horizontal scroll even if contents exceed the wrapper.
vScroll, same as above for vertical scroll.
By default, when creating a new iScroll('idOfElement') the scroll is vertical and horizontal. It can be disabled with these parameters. Dual Scroll is totally possible as this video shows it.
So, to force dual Scroll :
var myScroller = new iScroll('idOfElement', {vScroll:true, hScroll:true});

This is not a complete solution, but this might help you.
First of all, The HTML code was not properly nested, and so you were needed to put the <div> inside the <b>. I fixed up the HTML a bit and its working without the <b>
http://jsfiddle.net/Aexhz/
And with properly nested HTML and correct settings, This worked even after dividing the HTML/JS/CSS
For me, it does show some Horizontal as well as Vertical Scrolling, but i don't know if that's how you want it to be. i Edited the Class initialization line as well
myScroll = new iScroll('scroller1', {desktopCompatibility:true});
TO
myScroll = new iScroll('scroller1', {
snap: true,
momentum: false,
hScrollbar: false,
vScrollbar: false,
desktopCompatibility: true
});
This doesn't affects much but i still put that.
I will continue looking into this and update my answer if i find anything new.

I know you want to fix this using iscorll but wanted to share this with you, i had great results using it: http://jscrollpane.kelvinluck.com/#usage
It is highly customizable with css, a demo here with vertical and horizontal scroll: http://jscrollpane.kelvinluck.com/basic.html

javascript overlay not covering full page when div expands the page height

I realize there's already been several questions like this, but I think my case is a little different.
I have an div that I am absolutely positioning and floating on top of the page, and I'm setting an overlay behind it to grey out the rest of the page. I have it working okay until you scroll up and down the page.
The problem is, when the div appears, it is still populating with ajax data. So the height and width of the bg overlay has already been set, but once all the data loads into the floating div, it sometimes pushing the page down so the height increases. So, I can't calculate the height and width of the window or document because the floating div might not be fully loaded yet, and once it does, it pushes the screen down further, causing the bg overlay to not cover the whole page.
So for example, in the code it's going something like:
loadBoxContent = function(){
..DO AJAX HERE..
..PUT CONTENT INTO FLOATING DIV..
$('#floatDiv').show()
$('#darkOverlay').height($(window).height());
}
I verified this by adding an alert, so that by the time I've clicked the alert, the bg overlay was able to calculate the true page size, and it looks fine.
Sorry, if this sounds confusing but hopefully you get what I'm trying to achieve. I'm assuming this isn't too difficult, but I haven't been able to figure it out.
Any help would be appreciated, I'm using jquery.
Thanks

Overlay ;)
** update, setting position of all corners to 0 instead of using width/height 100% **
$("<div/>")
.css({
position:"fixed", // ze trick
background:"#000",
opacity:.5,
top:0,
bottom: 0,
left:0,
right: 0,
zIndex: 2999 // everything you want on top, gets higher z-index
})
.appendTo("body");
Or put the above css settings in a css stylesheet (opacity needs cross browser hacks).
$("#dark-overlay").show();

Here is the solution :
JQuery Show Loading Plugin
Don't try to invent the wheel !!!
Here is a demo :
Loading Demo
Now you just need to create a main container div for your page and just ask this simple plugin to do it for you.
Maybe you want to read the plugin source and find how it works...