Develop Reference

jQuery scrollTop() returns wrong offset on scroll-direction change

I'm trying to get the correct scroll direction via jQuery's "scroll" event.
For this, I'm using the solution here: https://stackoverflow.com/a/4326907/8407840
However, if I change the direction of my scroll, the offset returned by scrollTop is incorrect on the first time. This results in the following behavior:
Wheel down -> down
Wheel down -> down
Wheel up -> down
Wheel up -> up
Wheel down -> up
Wheel down -> down
... and so on, I think you get it.
var ACTIVE_SECTION = null;
var ANIMATION_DURATION = 700;
$(document).ready(function() {
ACTIVE_SECTION = $("section:first-of-type").get(0);
var prevPosition = $(window).scrollTop();
$(window).on("scroll", function() {
doScrollingStuff(prevPosition);
});
});
function doScrollingStuff(prevPosition) {
var ctPosition = $(window).scrollTop();
var nextSection = ACTIVE_SECTION;
// Remove and re-append event, to prevent it from firing too often.
$(window).off("scroll");
setTimeout(function() {
$(window).on("scroll", function() {
doScrollingStuff(prevPosition);
});
}, ANIMATION_DURATION + 100);
// Determine scroll direction and target the next section
if(ctPosition < prevPosition) {
console.log("up");
nextSection = $(ACTIVE_SECTION).prev("section").get(0);
} else if(ctPosition > prevPosition) {
console.log("down");
nextSection = $(ACTIVE_SECTION).next("section").get(0);
}
// If a next section exists: Scroll to it!
if(typeof nextSection != 'undefined') {
var offset = $(nextSection).offset();
$("body, html").animate({
scrollTop: offset.top
}, ANIMATION_DURATION);
ACTIVE_SECTION = nextSection;
} else {
nextSection = ACTIVE_SECTION;
}
console.log(ACTIVE_SECTION);
prevPosition = ctPosition;
}
section {
width:100%;
height:100vh;
padding:60px;
box-sizing:border-box;
}
section:nth-child(1) { background:#13F399; }
section:nth-child(2) { background:#14FD43; }
section:nth-child(3) { background:#4EE61E; }
section:nth-child(4) { background:#BEFD14; }
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<section id="sect1">Section 1</section>
<section id="sect2">Section 2</section>
<section id="sect3">Section 3</section>
<section id="sect4">Section 4</section>
Here's a pen, where you can see my implementation: https://codepen.io/EigenDerArtige/pen/aVEyxd
I am trying to accomplish an autoscroll to the next or previous section, whenever the user scrolls or swipes up/down... Therefore I only fire the "scroll"-event once every second, to prevent multiple scrolljacks all happening at once... However the above behavior seems to result in the user being scrolled to the wrong section.
I've been trying for a couple of hours now to get it working, but to no avail. Help is greatly appreciated!

The problem lies in the assignment prevPosition = ctPosition.
Each time the scroll handler runs, var ctPosition = $(window).scrollTop(); is good for determining scroll direction, however it's not the value that should be rememberad as prevPosition.
prevPosition needs to be $(window).scrollTop() as measured after the animation has completed.
Try this :
$(document).ready(function() {
var ANIMATION_DURATION = 700;
var ACTIVE_SECTION = $("section:first-of-type").eq(0);
var prevPosition = $(window).scrollTop();
$(window).on("scroll", doScrollingStuff);
function doScrollingStuff(e) {
$(window).off("scroll");
var ctPosition = $(window).scrollTop();
var nextSection = (ctPosition < prevPosition) ? ACTIVE_SECTION.prev("section") : (ctPosition > prevPosition) ? ACTIVE_SECTION.next("section") : ACTIVE_SECTION; // Determine scroll direction and target the next section
// If next section exists and is not current section: Scroll to it!
if(nextSection.length > 0 && nextSection !== ACTIVE_SECTION) {
$("body, html").animate({
'scrollTop': nextSection.offset().top
}, ANIMATION_DURATION).promise().then(function() {
// when animation is complete
prevPosition = $(window).scrollTop(); // remember remeasured .scrollTop()
ACTIVE_SECTION = nextSection; // remember active section
$(window).on("scroll", doScrollingStuff); // no need for additional delay after animation
});
} else {
setTimeout(function() {
$(window).on("scroll", doScrollingStuff);
}, 100); // Debounce
}
}
});

Change scrollTop offset when scrolling up, and different offset on scrollDown

I got an issue, where I have an dynamic header that gets bigger when scrolling up and smaller when scrolling down and therefore needs to change scrollTop offsets.
So i've been looking around and tried with my no existent java skills with no success.
This jquery code:
$(document).on('click', 'a[href^="#"]', function(e) {
var id = $(this).attr('href');
var $id = $(id);
if ($id.length === 0) {
return;
}
e.preventDefault();
// top position relative to the document
var pos = $(id).offset().top-500; // move this one
$('body, html').animate({scrollTop: pos});
});
var iScrollPos = 0;
$(window).scroll(function () {
var iCurScrollPos = $(this).scrollTop();
if (iCurScrollPos > iScrollPos) {
var pos = $(id).offset().top-500; //here when scrolling down
} else {
var pos = $(id).offset().top-100; // Here when scrolling up
}
iScrollPos = iCurScrollPos;
});
I made a JS fiddle to show what I'm trying to achieve: https://jsfiddle.net/zq9y7nge/1/
So, Is it possible to change offset depending on scrolling up and down?

Scrolling sidebar inside a div with scrollbar - $(window).on('scroll', function()?

I want my social sidebar make scroll only within the gray div. I have already put the sidebar within the gray div does not exceed the footer or the content above. My difficulty is to sidebar scroll accompanying the scroll without going gray div.
http://test.eae.pt/beautyacademy/angebot/
JS:
beautyAcademy.sharer = {
element: void 0,
elementToScroll: void 0,
init:function() {
this.element = $('.js-sharer-ref');
console.log(this.element.length);
if(this.element.length != 1) {
return;
}
this.build();
},
build: function() {
this.binds();
},
binds: function() {
var _this = this;
// Element that's gonna scroll
this.$elementToScroll = $('.fixed-social');
// Element that's gonna scroll height
this.elementToScrollHeight = this.$elementToScroll.outerHeight();
// Element where scroll is gonna happen Height
this.elementHeight = this.element.outerHeight();
// Element where scroll is gonna happen distance to top
this.elementOffsetTop = this.element.offset().top;
// Scroll that was done on the page
this.windowScrollTop = $(window).scrollTop();
this.elementOffsetBottom = this.elementOffsetTop + this.elementHeight - this.elementToScrollHeight;
this.$elementToScroll.css('top', (_this.elementOffsetTop+80) + "px");
$(window).on('scroll', function() {
if(this.windowScrollTop + this.elementToScrollHeight < this.elementHeight )
this.$elementToScroll.css('margin-top', this.windowScrollTop );
});
}
};

You need to try like below :
$(function(){
if ($('#container').length) {
var el = $('#container');
var stickyTop = $('#container').offset().top; // returns number
var stickyHeight = $('#container').height();
$(window).scroll(function(){ // scroll event
var limit = $('#footer').offset().top - stickyHeight - 20;
var windowTop = $(window).scrollTop(); // returns number
if (stickyTop < windowTop){
el.css({ position: 'fixed', top: 0 });
}
else {
el.css('position','static');
}
if (limit < windowTop) {
var diff = limit - windowTop;
el.css({top: diff});
}
});
}
});
DEMO

Reposition DIV after scrolling

I have a navigation bar that repositions after scrolling down. It works with position:fixed, but while scrolling I want it to move up like all the other content that follow on the site . I the user stops scrolling it should reposition on top:
Heres a demo:
http://jsfiddle.net/gvjeyywa/7/
But I want it to be position:absolute (especially for the scrolling on the Ipad)
http://jsfiddle.net/gvjeyywa/5/
How do i let the JS overide my CSS? Here is my JS:
var isInAction = false;
var lastScrollTop = 0;
$(window).scroll(function(event){
var st = $(this).scrollTop();
if (st > lastScrollTop){
if (!isInAction){
isInAction = true;
$( "#navigation" ).animate({
top: "-" + $("#navigation").innerHeight() + "px"
}).delay(1000).animate({
top: "0px"
}, 800, function() {
isInAction = false;
});
}
}
lastScrollTop = st;
});

In the first look i think it's impossible but after some tries this code was created.
I spent long time to write this code and use several techniques and hope to be helpful.
Maybe there are simpler solutions too !!
var bitFlag = false;
var lastScrollTop = 0;
var timeoutId;
$navigation = $("#navigation");
$(window).scroll(function (event) {
var intWindowTop = $(window).scrollTop();
var intElementBottom = $navigation.offset().top + $navigation.innerHeight();
if (intWindowTop > lastScrollTop) {
if (!bitFlag) {
$navigation.css("position", "absolute").css("top", intWindowTop + "px");
bitFlag = true;
}
if (timeoutId) {
clearTimeout(timeoutId);
}
timeoutId = setTimeout(function () {
if (intWindowTop > intElementBottom) {
intDelayTime = setTimeout(function () {
$navigation.animate({
top: intWindowTop + "px"
}, 800);
}, 500);
}
}, 100);
} else {
$navigation.css("position", "fixed").css("top", "0px");
bitFlag = false;
}
lastScrollTop = intWindowTop;
});
The }, 500); section control Delay time in milliseconds and the }, 800); section control the slide down animation speed.
Check JSFiddle Demo

jQuery curtain scroller app

I'm trying to build a curtain slider - much like what is used on the Apple site - http://www.apple.com/30-years/
http://jsfiddle.net/NYEaX/405/
I've created the following code - I need to add listeners to detect the mouse hovering over the far left/far right sides of the page - and then invoke an exponential slide.
var curtainSlider = {
invoke: function(el){
var that = this;
var list = $(el + " ul").find("li");
this.initialListWidth = list.outerWidth(true);
list
.mouseover(function() {
console.log("over");
that.expand(this);
})
.mouseout(function() {
console.log("out");
that.contract(this);
});
},
expand: function(el){
var that = this;
$(el).stop().animate({
width: that.initialListWidth*2
},400, function() {
// Animation complete.
});
},
contract: function(el){
var that = this;
$(el).stop().animate({
width: that.initialListWidth
},400, function() {
// Animation complete.
});
}
}
$(document).ready(function() {
console.log( "ready!" );
curtainSlider.invoke("#curtain");
});

**LATEST CODE - complete integration - http://jsfiddle.net/NYEaX/538/ **
I have stabilized this version of the scroller. - This curtains the images and spectrum fades them on start up. It repositions the a elements so the image is more centrally aligned.
http://jsfiddle.net/NYEaX/432/
I've separated out the code responsible for moving the slider unit, with an acceleration/deceleration. Its this part of the application I wish to focus on now.
http://jsfiddle.net/NYEaX/434/
I've tried to push the pagex variable into the animation part to help manipulate the duration of the animation. How can this be stabilized/improved on. I am finding it hard to reverse engineer the apple 30 year slider.
var curtainSlider = {
bindEvents: function(){
var that = this;
$("body").on("mousemove",function(event) {
if (event.pageX < 50) {
// animate curtain left
console.log("curtain left");
that.scroll("l", event.pageX);
}
if (event.pageX > (window.width - 50)) {
// animate curtain right
console.log("curtain right");
that.scroll("r", window.width - event.pageX);
}
});
},
scroll: function(direction, leveler){
var charge = "-";
if(direction == "r"){
charge = "+";
}
$('#curtainholder #slider').animate({
left: charge+"="+leveler
},400, function() {
// Animation complete.
});
},
invoke: function(el){
var that = this;
this.bindEvents();
}
}
$(document).ready(function() {
curtainSlider.invoke("#curtain");
});