How to change css styles on scroll without delay - javascript

Hi everyone,
I'm working on a side navigation menu for my churches website. You can see the demo here:
http://amightywind.com/sideNav/
However I have a problem. The navigation is supposed to work so when you scroll down the page past it's bottom the css changes to make it anchor and stop moving.
The problem is that the "anchoring" effect doesn't always work smoothly and will only be applied after you scrolled a few pixels past the bottom.
This causes the side bar to "jump" back into it's designed place.
I know this problem is probably caused by asynchronous panning (the browser delays repainting when scrolling to keep a smooth frame rate).
I was going to call this unsolvable, but then I saw firefox's quantum browser page.
If you scroll down halfway, you will see a large pink box on the left that says "Firefox Quantum features".
The text changes positioning when you scroll into it similarly to how my side bar works. However 2 things are different.
1 there is no jump. It is perfectly smooth in every browser I tested.
I figured this could easily be because they are moving a smaller portion of content than I am, but....
2 when I inspect element I notice there is no css class/style change on the object when scrolled into it.
How is this possible? Is there a way to make this effect work without Javascript? Or at least more smoothly than I've done just listening to the window scroll event?
Any help would be much appreciated thank you!

Related

How to stop user input interrupting "ScrollIntoView" whilst in progress

Context
I am creating a site where there are sections stacked in rows, and each row takes up the full viewport.
I don't want the site to be scrollable normally, and would instead like the site to "snap" to the bottom of each section, so that I can then play out the animations taking up the full view port.
Issue
I took the approach of listening to scroll events, and then triggering a nextsection.ScrollIntoView when the user had scrolled far enough to snap to the next view.
This doesn't work well though, as the ScrollIntoView is interupted by user scroll activity, including the latent scrolling of the mouse that hangs around for about 300ms after you've scrolled.
I managed to get it sort of working by using a setTimeout(scrollIntoView(), 400), but this takes too much time and relies on the user not interacting with the site after scrolling.
I made a CodePen (here) showing the type of setup I'm working with, however to see the issue you need to open it as a webpage itself, as CodePen doesn't perform a smooth animation when using ScrollIntoView and just jumps there.
I need a smooth and uninterruptable animation as the site switches from one section to another, but as of yet I've found no working ways to implement this.
Thanks for any answers.

Sliding an element "up" over another as the user scrolls down, without fixed positioning?

The wording in the title is weird, apologies. It's hard to explain the effect.
I currently have this, it works best on Chrome:
http://mattluckhurst.com/dev/
My client wants each panel to slide up as the user scrolls down, covering the previous panel. I am currently accomplishing this by setting the "current" panel to have position:fixed and top:0 as soon as the page scrolls to it. The panels each have a z-index that corresponds to their vertical position on the page. So ideally:
You scroll down. when the next panel is halfway up the window, the scroll animates to get you all the way there, then that panel is snapped to the top so the next one can come in over it.
It's working pretty well in Chrome, but I am getting a lot of flickering and stuff elsewhere. Also on mobile it's a mess, but we really want a nice smooth swipe up down.
I know fixed elements can get pretty funky on mobile, so I am wondering if that is the problem, or if I should be using something other than just window scrolling for the animation / effect.
I see more complex parallax stuff all the time, so this should be pretty doable, I'm just not sure where to start.
Thanks for any help! Let me know if you need more info.
A few libraries that might help you:
https://github.com/dirkgroenen/jQuery-viewport-checker
https://github.com/janpaepke/ScrollMagic
https://github.com/matthieua/WOW
https://github.com/jlmakes/scrollReveal.js
https://github.com/Prinzhorn/skrollr

Endless Scrolling Background jumps at certain Viewport sizes

I am trying to create a parallax starscape. This is actually not difficult at all. I am using Velocity.js which makes the endless scroll very smooth. I have noticed though that at certain viewport sizes the image jumps for some reason. I have tried to research this problem and tinker with my code, but to no avail. I made a fiddle https://jsfiddle.net/hunterjr88/gkae3up5/1/ , to show what I am talking about. Resize the window and see the image jump as it scrolls.
$(document).ready(function(){
function infinite(){
$('#stars').velocity({'backgroundPositionY':['100vh','0vh']},
{duration: 2000,easing: 'linear'});
infinite();
}
infinite();
});
I don't know velocity.js but I can see the issue and can explain what is going on.
Your scroll detect an end in scrolling and since this is an infinite scroll, which will keep on scrolling without stop, when it detects the end it will jump the scroll back to the top, this is why you see this jump.
As I told you I don't know about velocity.js But you need to make sure that your scroll will keep on scrolling smoothly even when the end is detected.

Slow down/stop/pause scrolling at a specific pixel

I'm looking for a way to slow down scrolling between two specific pixels, for example 1 to 100 from the top. Would that be possible in any way?
Here's a link to a website that have that feature I'm looking for.
http://goo.gl/isH5o0
When you start scrolling the dark blue overlay div disappears using CSS3 Translate3d, but then the scroll seems to stop or go really slow, which makes the underlying div not scroll to far at the same time the overlay div slides up.
Can someone please give me a hint of what technique to use to accomplish this or maybe help me with some code.
I think that there's nothing special with the scroll on that page, just the divs moving using 3d transforms. But if you want to achieve special effects with scroll, you can use the jQuery animate function:
$('html').animate({scrollTop: position-to-scroll}, 300, 'ease-in');
More about animate.
It may be using disable scrolling. I noticed that if i drag the scroller on the right hand side of the window it is uneffected by the "slowing" however the mouse scroll is. This is similar to the effect of the demo described here How to disable scrolling temporarily? .. at a point you can temporarily disable the scroll and then re enable it to stop them going too far down

Prevent Body Element From Scrolling On Touch Devices

The Problem:
I have a web application on the iOS homescreen so there is no browser window and it looks and functions very well. I've figured out how to make inner div elements do the touch scrolling events and use the momentum/bounce style in iOS, and that works perfectly... the issue I run into now is that the bounce scrolling (again, iOS-only) is messing up any fixed elements or site-related animations I have on the page.
When I try the following:
document.ontouchmove = function(e) {e.preventDefault()};
The issue stops, but now I can't scroll anywhere on my application.
What I Need:
I want the body to be completely locked in place... If someone grabs, say, my sidebar or navbar and then pulls on the page, the body bounces! But if someone is inside the content area, there is no issue at all--the application scrolls flawlessly and looks great. If I stop scrolling on the sidebar or navbar or body, all scrolling in the application will not working and is essentially nonfunctional.
tl;dr: Body bounces on scroll. I want a scrolling content area and no scroll anywhere else. The body should NEVER move, but elements I deem scrollable within the body should.
As a sidenote, I've browser the following popular questions/solutions posted (among many others):
1
2
3
I just wanted to post that up before people assumed I didn't do any searching... I've been at this for hours now and have seen even more solutions than posted above, but I wanted to get the most popular ones listed above so no one thought this was a duplicate question.
I figured this out a few days ago and have this handy jsbin set up to demonstrate what I did to make this work:
My Working jsbin Example
When you open this link on an iPad, the text should be scrollable. Try tugging around the rest of the screen when there is no current touchmove event currently working.
If you play around with it, you'll notice that only the inner textfield moves as expected. This is determined by putting my .scrollable class within the .container class. The .scrollable class takes up the full height of it's parent container.
Now make the container a larger height, like height: 500px. The goal here is to make it large enough to have no overflow yet small enough to have other whitespace on the iPad still. Try scrolling it or pulling it... No touchmove events are fired and the screen stays in place.
My JS determines if an object has overflow after being touched. If it does, it scrolls. If it does not, it does not send a scroll event.
Play with it and let me know if I can provide any better examples and also if you run into any bugs... Right now the only one I know of is if you're really trying to break it and start tugging around the site while a current touchmove event is being fired, or the page is first loading... I wouldn't count those as "bugs", but if you can find a fix for those too, I'm all ears!

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