This page uses a bit of JS to prevent the top of the left-side panel from scrolling past the top boundary of the viewport.1
Under Chrome 31 and Firefox 25, the left-side panel remains rock-solid as one scrolls past the top of the containing div, but in other browsers (e.g. IE 11 and Safari 6) the left-side panel "bounces" vertically as one scrolls. (Once the scrolling stops, the position of the left-side panel stabilizes.)
Here's the JS/jQuery code responsible for this effect:
(function () {
var w = $(window),
lc = $('.left-panel');
w.scroll(function () {
var st = w.scrollTop(),
ot = lc.offset().top;
$('.vfloat').css('top', Math.max(0, st - ot));
});
}());
Question: How can I eliminate this unwanted "bouncing" of the left-side div?
EDIT: cleaned up and simplified the code snippet.
1To make this effect possible, you may need to resize your window's vertical dimension so that enough of the right-side panel falls outside the viewport.
It is the way each browser fires scroll event. You use height calculations which are very expensive and cause reflows of the webpage, and it depends on browser how it handles that.
I can suggest you 2 options that will solve your problem:
1) Simply use jQuery animate to change position of your left div, that way the position will change smoothly, you can use even very fast speeds. If you don't want to use jQuery you can simulate the same behavior by writing your own code and using timers to change top position smoothly or even css3 animations.
2) The second way (and I think this is the preferred way) is not to use javascript for position manipulation in this case and use javascript only to assign position: fixed class to your left container on some conditions. It will still cause reflows, but you won't have such delay caused by scroll event.
Solution 1 - using css3 transition and jQuery for smooth animation: http://jsfiddle.net/6bYhx/4/ (the same can be accomplished with jQuery.animate())
Solution 2 - using position: fixed and addClass (the problem with IE still persists as scroll event is delayed): http://jsfiddle.net/S5Sgu/
So I think that the optimal solution would be smooth animation (Technique 1) with some modifications.
Related
Similar to this unresolved question (jQuery - parallax - update background position correctly)
I am animating the transform property of an element on page scroll to achieve a parallax-like effect. I want this element to only begin animating up when it is in view. The problem now is that if the element appears further down the page, it has already moved up a lot and loses the effect.
Here is my code currently
function parallax() {
var scrolled = $(window).scrollTop();
$('[data-scroll]').css('transform', 'translateY('+-(scrolled*0.02)+'px)');
}
$(window).scroll(function(e){
parallax();
});
In answer to your question how to separate "parallax'ed" divs, so they shift their position independently from each other upon scrolling, one should rely on their unique coordinates - each one has it's own $(elem).offset().top - a general vertical offset from the top of the page (it's stays the same all the time unless you meddle with the TOP property manually).
so all calculation could be based against this property.
$('.parallax').each(function(){
if ($(this).is_on_screen()) {
var firstTop = $(this).offset().top;
var winScrollTop = $(window).scrollTop();
var shiftDistance = (firstTop - winScrollTop)*0.02;
$(this).css("transform":"translateY("+shiftDistance+"px)");
}
});
plus you check if the element is in the viewport. Thus, you assure it moves the same delta distance in its own time no matter where it's on the page - further down or up.
Another thing is that how to put "borders" of visibility of the element on the screen. If you are moving an element when it's in viewport, i would suggest making a wrapping div within which the movement occurs (like a bg moving within a div wrapper).
<div class="parallax-section slide1">
<span class="moving-block"></span>
</div>
div has a bigger height and we check when this div is on the screen, not the moving element.
demo
Also other modifications can be applied if one needs different speed, offset for each element. I found this plugin a good beginner stuff to learn parallax.
P.S. btw, all initial properties should be cached in variables instead of retrieving them each time in a callback, like firstTop for instance
I have a div that gets a 'fixed' class added to it once the user scrolls past a certain point in the parent div. The fixed class simply changes the child div from absolute positioning to fixed positioning.
However, a problem occurs when the user scrolls to a certain point when the 'fixed' class is added (as specified by the 'begin variable' in the js). The user loses the ability to scroll up or down for a number of seconds. And to make matters more complicated, this problem only occurs on the first of six parent divs that uses this code.
Here's the jquery code that adds the 'fixed' class:
var begin = 164;
$("#portfolio_window").scroll(function () {
var y = $(this).scrollTop();
if (y >= begin) {
$('.details').addClass('fixed');
} else {
$('.details').removeClass('fixed');
}
});
If I change the 'begin' variable to something like 600, the user loses the ability to scroll around 600px from the top of the div.
You can try to reproduce the problem at http://dev.zachboth.com/
Here's the easiest way that I've been able to reproduce the problem:
Use Safari
Clicking 'Various Logos' in the 'Work' section
Scrolling down quickly once the 'Various Logos' section appears
It may take several attempts to actually have the problem occur
I can explain your problem:
The problem is that on the "page" you mention being broken has you scrolling in div#portfolio_window. The position:fixed element you mentioned is positioned relative to the window. When you scroll on that element, it's trying to scroll the window (not the parent div).
http://jsfiddle.net/NThY7/
The solution is a bit more involved. I'll hop back on later with a solution.
Any idea how make a layout like google plus or facebook. You can see at google plus home as example,
at the beginning, if you scroll the page in the main content, they will scroll together (friend post and sidebar), but when you scroll until the bottom of sidebar (in the right of friend post), that sidebar will stop scrolling , but the another content (friend post) will still scrolling. can explain to me how to make layout like that? sample code or demo will be very help.
Fixed positioning with CSS is a very limited approach. There are a number of ways to do this style of "fixed" areas, many of which have already been given in answers to similar questions on here (try the search above?).
One technique (which many are based on) is like so (in brief)..
Capture the browser's scrolling
Get the position from top of chosen element (x)
Check if the scrolling > x, if so apply a class to the element to fix it to a certain position.
The same will work in reverse, for example:
var target = $('#div-to-stick');
var div_position = target.offset().top;
$(window).scroll(function() {
var y_position = $(window).scrollTop();
if(y_position > div_position) {
target.addClass('fixed');
}
else {
target.removeClass('fixed');
}
}
Note: Depending on how you chose to complete the code above, the page will often "jump" as the div's position is modified. This is not always a (noticeable) problem, but you can consider getting around this by using .before with target.height() and appending a "fake" replacement div with the same height.
Hope this helps.
The new approach with css3 is reduce your effort. use single property to get it.
position:sticky;
here is a article explained it and demo.
article
Demo
You are looking for CSS position:fixed (for the scroll-along sidebar), you can set the location with left:[length], right:[length], top:[length], bottom:[length] and the normal width and height combos
You will need to augment it with a window resize and scroll listener that applies the position:fixed property after the window has scrolled past the top of the sidebar.
Use css property (position:fixed). This will keep the position of the div fixed even if you scroll down or scroll up.
Quick question...
Is there any way to change the default behavior of a scrollbar from moving one pixel at a time (continuous motion), to jumping say 100px at a time (less continuous more discrete jumps). I have an animation that jumps between pictures and I want to use the scrollbar to show one picture at a time.
Whenever I try changing the behavior of the scrollbar it either jumps all over the place or does some screwy stuff. BTW I'm scrolling the bar, not using arrows to move it. That way I can manually make the animation faster or slower.
Use the Control.ScrollBar.scrollBy() function to scroll by any number of pixels.
var scrollbar = new Control.ScrollBar('scrollbar_content','scrollbar_track');
$('scroll_down_50').observe('click',function(event){
scrollbar.scrollBy(-50);
event.stop();
});
EDIT: To disable the scrollbar try: scrollbar.disable()
From: http://livepipe.net/control/scrollbar
I want to postion a DIV inside a page such that it is visible to the user even if the user vertically scrolls the page.
The page has a heading at the top of the page which is 75 px tall. Now when the user is at the top of the page and has not scrolled vertically, the DIV must be postioned below the heading. However, once the user scrolls the page causing the heading to go out of sight, the same DIV must now be position at the top of the page (i.e. near the top edge of the browser viewport)
My big concern is the support for window.onscroll event on browsers. I checked QuirksMode for compatibility (http://www.quirksmode.org/dom/events/scroll.html). It seems to have decent compatibility on IE and Firefox. However the Safari and Chrome support seems a bit quirky. And both these browsers are part of my target browsers' list.
Can anybody tell me if the window.onscroll event is an effective way of detecting page/frame scrolls? Any other suggestions?
P.S. I have considered using the CSS position: fixed rule. It is close to the solution but the DIV is just stuck to one position and I cannot have it adaptively move based on the visiblity of the heading.
Thanks!
Here's another alternative method you could try. I use it to position a toolbar div on top of the page (works for ipad too).
Instead of using the onScroll event, I am using a timer to fire every 500ms to detect where the windows is scrolled to via scrollTop . You could adjust the timer to about 200ms if you like.
Here's a stripped down sample of my code:
This jquery code checks when and if my dom element div named "floatlayer" (which is a div that contains my buttons toolbar) is ready and then calls the function setRepeater
$(#floatlayer").ready(function () {
return setRepeater();
});
Then, this is the function that creates a timer to keep executing the function "keepIncrease" every 500ms
function setRepeater() {
aTimer = window.setInterval("keepIncrease()", 500);
return false;
}
This is the function keepIncrease() which is repeated every 500ms and is responsible to position the toolbar div based on the current window scrolled position :
function keepIncrease() {
var divToolbar = $("#floatlayer")[0];
var currentPos = $(window).scrollTop();
divToolbar.style.top = currentPos + "px";
return false;
}
Something else out of topic:
If your content is inside an iframe, you could also use $(window.parent).scrollTop() instead of $(window).scrollTop()
If you read about the clunkiness in WebKit on Quirksmode, you'll notice the following:
Safari (but not on iPhone) and Chrome seem to monitor scrollTop acces in order to determine whether the user has scrolled an element. The log function of my test script changes scrollTop regularly, and Safari responds by firing a scroll event. Since the logging of this event changes the log element's scrollTop once more, scroll events will be fired continuously.
All this happens when the log element at the bottom of the page doesn't have a scrollbar yet, when it has a normal overflow: visible, and even when I set scrollTop to 0 each time a new event is logged. The buggy behaviour stops only when I remove the scrollTop line entirely.
This issue shouldn't affect what you're trying to achieve since you're not setting the scrollTop of any element. You're attaching onscroll to the window, which appears to have no issues between any browser anyway.
Why not just use "fixed"?
Oh, I see, I missed the part about the header.
You could still utilize the position:fixed option, though. You would just set the position against "body" initially (accounting for the 75px gap), and once the header leaves viewability, you can realign the div against the top of the viewport. But without using onscroll in some way or another you probably won't be able to do what you want to do. Sometimes you just have to make the decision: Do I want the feature more, or the people more?