Develop Reference

Show logo if site has scrolled

I have a header with a logo. This logo should appear only if the site has been scrolled.
I tried this in javascript:
if(document.getElementById("div").scrollTop != 0){
document.write("<img src='logo.jpg'>");
}
But this did not work.
How to achieve it?

Use window.addEventListener('scroll', callback) and then set the value "block" to the img's property.
window.addEventListener('scroll', function(e) {
if (document.getElementsByTagName("html")[0].scrollTop > 5) {
document.getElementsByClassName('imgHeader')[0].style.display = "block";
} else {
document.getElementsByClassName('imgHeader')[0].style.display = "none";
}
});
.imgHeader {
height: 100px;
width: 100px;
display: none;
}
div {
height: 1000px;
}
header {
position: fixed;
top: 0;
width: 100%;
}
<header><img class="imgHeader" src="https://material.angular.io/assets/img/examples/shiba1.jpg" /></header>
<div></div>

Try this one
$(document).on("scroll", function() {
if ($(document).scrollTop() > 5) {
$(".below-top-header").addClass("show-class");
} else {
$(".below-top-header").removeClass("show-class");
}
});
.content {
height: 500px;
}
.show-class {
position: fixed;
display: block !important;
}
.hide-class {
display: none;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="content">
<div class="below-top-header hide-class">
Image
</div>
</div>

Unfortunately, I think you must use some JavaScript to make it work like you want.
Here is an easy snippet to show the principle I used:
Start with the logo already in the html, but with display: none in its CSS,
Use window.addEventListener('scroll', callback) to change display: none to display: block when the page is scrolled down (i.e. document.documentElement.scrollTop > 0).
var logo = document.getElementById('logo');
window.addEventListener('scroll', function(e) {
if (document.documentElement.scrollTop > 0) {
logo.style.display = 'block';
}else logo.style.display = 'none';
});
#logo {
display: none;
position: fixed;
top: 0;
background: #aaa;
}
#page {
background: #ddd;
height: 2000px;
}
<div id='logo'><img src='http://placekitten.com/200/50'></div>
<div id='page'>Start of page<br>Try to scroll down</div>
Hope it helps.

You need to add an scrollListener to the window in order to execute code when the user scrolls.
Your code only gets executed on page load.
Informations on Eventlisteners: https://developer.mozilla.org/de/docs/Web/API/EventTarget/addEventListener
window.addEventListener('scroll', function(e) {
//do something as soon as the window was scrolled
});
Be aware that the event will be triggered each time the user scrolls.

Add/remove class with jQuery based on scroll

So basically I'd like to remove the class from header after the user scrolls down a little and add another class to it. Trying to figure out the simplest way of doing this but I can't make it work here is the code
$(function() {
var $sectionBox = $(".J_section-box"),
$navbarBox = $(".J_nav-bar-con"),
navHeight = $(".J_nav-bar-con").height();
$(window).on("scroll", function() {
$(window).scrollTop() >= $sectionBox.offset().top - navHeight ? $navbarBox.addClass("J_fixNavbar") : $navbarBox.removeClass("J_fixNavbar")
});
});

For simplicity, I would suggest to use toggleClass, what makes it a bit easier and better to maintain.
$(function() {
var $navbarBox = $(".J_nav-bar-con");
var navHeight = $(".J_nav-bar-con").height();
$(window).on("scroll", function() {
$navbarBox.toggleClass("J_fixNavbar", $(this).scrollTop() >= $(".J_section-box").offset().top - navHeight);
});
});
.content {
width: 100%;
height: 10000px;
}
.J_nav-bar-con {
width: 100%;
height: 100px;
background: gray;
position: fixed;
top: 0;
}
.J_section-box {
width: 100%;
height: 100px;
margin-top: 200px;
}
.J_fixNavbar {
background: red;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="J_nav-bar-con"></div>
<div class="J_section-box"></div>
<div class="content"></div>

Vertically fixed navigation bar

I would like to create vertically a fixed navigation bar for my site. Currently i use the one that has been mentioned on various posts here:
HTML:
<html>
<head>
src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<link rel="stylesheet" type="text/css" href="{% static 'navbar.css' %}">
<script type="application/javascript">
$(document).ready(function () {
var navPos = $('.nav_menu').offset().top; //Sticky navbar
$(window).scroll(function () {
var scrollPos = $(this).scrollTop();
if (scrollPos >= navPos) {
$('.nav_menu').addClass('fixed');
} else {
$('.nav_menu').removeClass('fixed');
}
});
});
</script>
.....
<div class="nav-container">
<div class="nav_menu">
Bars go here
....
And CSS:
.nav-container .nav_menu.fixed {position: fixed; z-index: 10000; top: 0; width: 195px; padding-left: 8px}
This solution works great, the navbar is sticked, in my case the navbar is on the top left side of the page. If i scroll down it perfectly follows the scroll. In case i open the gape using a small window and i stoll down plus right the bar follows (as it should happen). However i would like the bar to only follow vertically, in case someone scrolls left or right the bar should stay where it is.
How can i achieve this?

You can stop the horizontal fixed by applying minus left scroll:
var $window = $(window);
var navPos = $('.nav_menu').offset().top; //Sticky navbar
$window.scroll(function() {
var scrollPos = $window.scrollTop();
var left = 0 - $window.scrollLeft();
if (scrollPos >= navPos) {
$('.nav_menu').addClass('fixed').css('left', left + 'px');
} else {
$('.nav_menu').removeClass('fixed').css('left', 0);
}
});
body,
html {
height: 1000px;
width: 2000px;
position: relative;
margin: 0;
padding: 0;
}
.nav_menu {
height: 50px;
background-color: blue;
width: 195px;
}
.fixed {
position: fixed;
top: 0;
left: 0;
z-index: 2;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<br><br><br>
<div class="nav_menu"></div>

Horizontal scroll at the middle of the page

I want to change the scroll direction at the middle of the page.
I tried to do it with "jInvertScroll", but this plugin increase left in css, like that:left: /* increase on scroll */ px ;
So if I want to change the scroll direction to the middle of the page, left will already have a value like:left: -1500px;
That's my problem.
Is there another way to do it?
HTML :
<div class="vertical"></div>
<div class="menu-change"></div>
<div class="horizontal">
<p>scroll</p>
</div>
CSS :
body {
overflow-x: hidden;
padding: 0;
margin: 0;
}
.scroll {
position: fixed;
bottom: 0;
left: 0;
}
.vertical {
width: 100vw;
height: 2500px;
background-image: url(https://source.unsplash.com/random);
}
.horizontal {
width: 8500px;
height: 100vh;
background-image: url(https://source.unsplash.com/random);
}
JS :
$(document).ready(function(){
var scroll_start = 0;
var startchange = $('.menu-change');
var offset = startchange.offset();
$(document).scroll(function() {
scroll_start = $(this).scrollTop();
if(scroll_start > offset.top) {
$('.horizontal').addClass('scroll');
var elem = $.jInvertScroll(['.scroll'],
{
onScroll: function(percent) {
console.log(percent);
}
});
$(window).resize(function() {
if ($(window).width() <= 0) {
elem.destroy();
}
else {
elem.reinitialize();
}
});
} else {
$('.horizontal').removeClass('scroll');
}
});
});

Position fixed till before footer

I have the following code:
<html>
<head>
<script src="http://code.jquery.com/jquery.min.js" type="text/javascript"></script>
<script>
$(window).on("scroll",function(e){
var sidepos = parseFloat($('#footer').offset().top - $('#side').outerHeight());
if($(window).scrollTop() > 100 && $('#side').offset().top < sidepos) {
$('#side').css('position','fixed');
$('#side').css('top','0');
}
else if($(window).scrollTop() > 100 && $('#side').offset().top >= sidepos) {
$('#side').css('position','absolute');
$('#side').css('top','' + sidepos + 'px');
}
else if($(window).scrollTop() < 100) {
$('#side').css('position','');
$('#side').css('top','');
}
});
</script>
</head>
<body>
<div id="header"></div>
<div id="body">
<div id="side"></div>
</div>
<div id="footer"></div>
</body>
</html>
I want to keep the #side fixed while scrolling till before the #footer so that it doesn't overlap with it.
Now there are 2 problems:
If you scroll down quickly like pressing 'end' button on keyboard, the function will not execute and the side overlaps with the #footer ignoring the if condition.
After switching to position:absolute can't figure out how to fix again when scrolling up and the #side becomes permanently sticking with the #footer even if you scroll up again.
I created a fiddle for you to test: http://jsfiddle.net/JuD5h/

Here is your updated fiddle: http://jsfiddle.net/JuD5h/4/.
I made some changes to CSS:
#body {
height: 3000px;
position: relative;
}
#side {
width: 100px;
height: 350px;
float: left;
border: 1px solid #000000;
position: absolute;
top: 0;
}
And here is the updated Javascript:
$(function(){ // document ready
var maxAbsoluteTop = $('#body').outerHeight() - $('#side').outerHeight();
var minAbsoluteTop = 0;
$(window).scroll(function(){
var windowTop = $(window).scrollTop();
var actualTop = windowTop - 100;
if ( actualTop <= maxAbsoluteTop && actualTop >= minAbsoluteTop) {
$('#side').css({ top: windowTop - 100 });
} else if (actualTop > maxAbsoluteTop){
$('#side').css({ top: maxAbsoluteTop });
} else {
$('#side').css({ top: minAbsoluteTop });
}
});
});
Use of position: absolute has made the animation flickery but I hope that is something you can fix using a small delay.