Develop Reference

Scroll of window doesn't work

I have some div and I want that, when I click on one of them, it automatic scroll to the top of the current window.
So, I calculated the current position (relative to the window), I calculated the height of the window, and I animated scroll to the position given by the difference between the previous numbers. But it doesn't scroll. Why?
Full code: http://jsfiddle.net/8dhhbk9r/
JS code:
$('.post').each(function() {
var post = $(this);
post.text( post.position().top - $(window).scrollTop() );
post.click(function() {
var where = post.position().top - $(window).scrollTop();
var h = $(window).height();
var scrollTo = h - where;
post.animate({
scrollTop: scrollTo
}, 800);
});
});

$(".post").on("click", function(){
$("body, html").animate({'scrollTop': $(this).offset().top}, 1000 );
});//click

Scroll function scrolling infinitely; makes footer inaccessible

I am trying to implement a sidebar to follow the user's screen as he or she scrolls up or down in the browser page. However I am getting an issue where the sidebar continues to scroll down the page infinitely if the user keeps scrolling down.
var element = $('#movingBox'),
originalY = element.offset().top;
// Space between element and top of screen (when scrolling)
var topMargin = 100;
$(window).on('scroll', function(event) {
var scrollTop = $(window).scrollTop();
element.stop(false, false).animate({
top: scrollTop < originalY
? 0
: scrollTop - originalY + topMargin
}, 300);
});
Is there a way to limit the sidebar from scrolling too far down than its supposed to?

I hope I have understood your question. You want to stop the box following at a certain position like this ?
var element = $('#movingBox'),
originalY = element.offset().top;
// Space between element and top of screen (when scrolling)
var topMargin = 100;
$(window).on('scroll', function(event) {
var scrollTop = $(window).scrollTop();
var stop = $('#stop').offset().top; // or in pixel
stop -= $('#movingBox').height() + topMargin;
if (scrollTop<stop) {
element.stop(false, false).animate({
top: scrollTop < originalY
? 0
: scrollTop - originalY + topMargin
}, 300);
}
});
Try the example in JSFiddle

Update: Add more control: hide header on scroll and work from a certain width size

Updated this question again:
I have an existing script which works, but the only thing that I would like to have more control on is specifying the tolerance for up/down scroll and when it shows or hides the menu. Currently, the menu slides up at first after scrolling 44px (delta value)--which is OK--but after that, I would like the menu to scroll up or down directly on scroll. When you set the delta value to 0px you can see what i mean, but than it doesn't have the delay at the first scroll (understand it?).
Second thing is that i would like to add a function to the script that will let me control from which width it will start to work. I want it to work from 667px and downwards and not work when it is more than that value (some what like a media query).
JSFiddle
// Hide header on scroll down //
var didScroll;
var lastScrollTop = 0;
var delta = 44;
var navbarHeight = $('header').outerHeight();
$(window).scroll(function(event){
didScroll = true;
});
setInterval(function() {
if (didScroll) {
hasScrolled();
didScroll = false;
}
}, 250);
function hasScrolled() {
var st = $(this).scrollTop();
// Make sure they scroll more than delta
if(Math.abs(lastScrollTop - 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 > lastScrollTop && st > navbarHeight){
// Scroll Down
$('header').addClass('nav-up');
} else {
// Scroll Up
if(st + $(window).height() < $(document).height()) {
$('header').removeClass('nav-up');
}
}
lastScrollTop = st;
}

Two questions / two answers:
but after that I would like the menu to scroll up or down directly on scroll
set delta to 0
Also what is the 250 value? Can't seem to see what it does?
250 is the interval of the check if the user scrolled

Background scrolling with content matching top and bottom?

I have a page with a simple div. If the div is at the top of the page, the background image (a very long vertical wallpaper) should also only be displaying the top section. If we scroll all the way down, then at the last area way at the bottom, the bottom of the background will show. The effect is that it's like a parallax where the scrolling of the content and background image occur in tandem and are scaled to each other.
How would I do this?
Update: My attempt is something like this:
function setupMainContent(){
$("#programming").delay(1000).fadeIn(1000, function(){
$(window).scroll(function(){
var current = $(window).scrollTop();
var bottom = $(document).height() - $(window).height();
var scale = 100*(current/bottom);
$('body').css({
'background-position':scale+'%'
});
});
}
I don't really know how to work with variables within quotes however.
Update: I got it to work using this:
function setupMainContent(){
$("#programming").delay(1000).fadeIn(1000, function(){
$(window).scroll(function(){
var current = $(window).scrollTop();
var bottom = $(document).height() - $(window).height();
var scale = 100*(current/bottom) + "%";
document.body.style.backgroundPosition = "center " + scale;
});
});
}
But there seems to be very bad impact on performance. Is there any way to make it more responsive and faster?

CSS:
background-attachment: fixed;
https://developer.mozilla.org/en-US/docs/Web/CSS/background-attachment

This worked for me:
function setupMainContent(){
$("#programming").delay(1000).fadeIn(1000, function(){
$(window).scroll(function(){
var current = $(window).scrollTop();
var bottom = $(document).height() - $(window).height();
var scale = 100*(current/bottom) + "%";
document.body.style.backgroundPosition = "center " + scale;
});
*/
});
}

Jquery follow scroll

I have a sort of sidebar on my website, which has to scroll down together with the user so that it is always in the view.
The code I'm using now is actually working fine however there is one problem. On smaller screens the sidebar scrolls before your at the sidebar thus making it impossible to see it all even if you scroll.
So what I want is the sidebar to scroll with the bottom instead of it being pushed down with the top so that when you reach the end of the sidebar it starts to scroll.
This is the code that I'm currently using.
var documentHeight = 0;
var topPadding = 10;
$(function() {
var offset = $("#mainright").offset();
documentHeight = $(document).height();
$(window).scroll(function() {
var sideBarHeight = $("#mainright").height();
if ($(window).scrollTop() > offset.top) {
var newPosition = ($(window).scrollTop() - offset.top) + topPadding;
var maxPosition = documentHeight - (sideBarHeight);
if (newPosition > maxPosition) {
newPosition = maxPosition;
}
$("#mainright").stop().animate({
marginTop: newPosition
});
} else {
$("#mainright").stop().animate({
marginTop: 0
});
};
});
});

I guess the "best practice" for accomplishing a task like this is to use dynamically changing css position from absolute to fixed and vice versa. A basic example could look like:
$(function(){
var $box = $('.box'),
offset = $box.offset(),
doc_h = $(document).height();
$(window).scroll(function(){
if($(window).scrollTop() > offset.top) {
if(!$box.hasClass('fix'))
$box.toggleClass('normal fix');
}
else{
if(!$box.hasClass('normal'))
$box.toggleClass('normal fix');
}
});
});​
Example in action: http://www.jsfiddle.net/YjC6y/14/

$(function() {
var top = 50;
$(window).scroll(function() {
$('#box').stop().animate({ top: $(window).scrollTop() + top}, 1000);
});
});
Try the example : http://jsbin.com/omiyi3

I think you can instead make the sidebar responsive by throwing your function into one of these:
if (responsive_viewport >= 768) {}
This makes it so that the function will only load if the viewport is bigger than or equal to 768px.