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

animate scroll to specific page position on scroll

I'm trying to replicate the scroll event found on http://blkboxlabs.com/, when the user scrolls it animates the screen to the next full height section, depending on if they scroll up or down.
I've got similar functionality, but it is much less smooth, and if the user scrolls enough it will skip 2 sections, as opposed to stopping at the next section.
var didScroll;
var lastScrollTop = 0;
var delta = 5;
$(window).scroll(function(event){
didScroll = true;
});
setInterval(function() {
if (didScroll) {
hasScrolled();
didScroll = false;
}
}, 800);
function hasScrolled() {
var st = $(document).scrollTop();
var winTop = $(window).scrollTop();
var winBottom = winTop + ($(window).height());
// 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){
// Scroll Down
$('.fullHeightScrollAssist').each(function(index, element) {
var elTop = $(this).offset().top;
var elBottom = elTop + $(this).outerHeight();
if(elTop > winTop && elTop < winBottom){
$('.fullHeightScrollAssist').removeClass('activeFullScreen');
$(this).addClass('activeFullScreen');
$('html,body').animate({scrollTop: elTop}, 700);
};
});
} else {
// Scroll Up
$('.fullHeightScrollAssist').each(function(index, element) {
var elTop = $(this).offset().top;
var elBottom = elTop + $(this).outerHeight();
if(elBottom > winTop && elTop < winTop){
$('.fullHeightScrollAssist').removeClass('activeFullScreen');
$(this).addClass('activeFullScreen');
$('html,body').animate({scrollTop: elTop}, 700);
};
});
}
lastScrollTop = st;
}
You can see my example at https://jsfiddle.net/raner/vhn3oskt/2/
What I'm trying to accomplish:
1. run the animate scrollTop function immediately on scroll, only once.
2. kill any further scrolling once animation starts, to keep it from skipping the next section.

For anyone else who might like to know, here's a plugin I found that did something close to what I was looking for and was a lot smoother than my initial attempt.
http://www.jqueryscript.net/demo/jQuery-Plugin-For-Smooth-Scroll-Snapping-panelSnap/demos/

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;
});
*/
});
}

Basic Parallax - Background jerking up

I have a simple code for moving the background images, but the image is jerking up once the section is in view. the idea is for the background-pos to move only when the section is in view.
Any ideas?
$window = $(window);
$('.portfolioSection').each(function(){
var $bgobj = $(this); // assigning the object
var speed = 8;
$(window).scroll(function() {
if($(window).scrollTop() + 150 >= $bgobj.offset().top){
// Scroll the background at var speed
// the yPos is a negative value because we're scrolling it UP!
var yPos = -($window.scrollTop() / speed);
// Put together our final background position
var coords = '0 '+ yPos + 'px'
// Move the background
$bgobj.css({ backgroundPosition: coords });
}
}); // window scroll Ends
});

Solved it- I didn't account for the section position - Line 9
var yPos = -(($window.scrollTop()-$bgobj.offset().top) / speed);