I have seen various forms of this problem but nothing really helped me to solve the partial sticky sidebar/Bootstrap column behaviour. Let me start with the problem itself.
There is a big image close to the top of my page. Because of the page complexity, I am using Bootstrap column grid. The image spans over, let's say, 10 columns and I have left 2, belonging to the same row, on the left side to store a sidebar. This also allows me to vertically align the sidebar next to the image.
Now, the sidebar, what is now a Bootstrap column, should go sticky and should stay vertically aligned to the viewport once the scrollbar passes by. You can see in the fiddle that it kind of "jumps" instead of transitioning smoothly.
The other problem is that the sticky element/column should only remain sticky as long as its parent/container is visible. Which means that it should transition/be relative to the end of that container. Right now I have only managed to keep it sticky till the end of the page. It should stop above the red line (depicted in the fiddle).
Here is my jQuery logic so far.
$(document).ready(function(){
$(window).scroll(function(){
var elem = $("#refScroller").offset().top - ($("#refScroller").height() / 2);
var windowvalue = $(window).scrollTop();
if (elem <= windowvalue) {
$("#wannabeSticky").addClass("sticky");
}
else {
$("#wannabeSticky").removeClass("sticky");
}
});
});
I would really appreciate some ideas and hints as this has been bothering me for two days. I would love to keep the Bootstrap grid structure if possible, but feel free to give any suggestions, even those who depict the sidebar as a pure absolute div, as long as the sticky-ness works.
Thanks in advance!
EDIT: I know there is a similar problem already here, but it seems I can't make the JS logic work for my case.
So, having spent another day on it, it seems I reached a decent jQuery version that gets the job done. There is my updated fiddle.
$(document).ready(function(){
var passedMobileNavi = false;
function stickySocialNavi(reference, valueExtracted) {
var refTop = $(reference).offset().top - valueExtracted;
var scrollTop = $(window).scrollTop();
return (refTop <= scrollTop);
}
$(window).scroll(function() {
if (stickySocialNavi($("#refScroller"), $("#refScroller").height())) {
if (!passedMobileNavi) {
passedMobileNavi = true;
$("#wannabeSticky").addClass("sticky");
}
}
else {
passedMobileNavi = false;
$("#wannabeSticky").removeClass("sticky");
}
if (stickySocialNavi($("#end"), $(window).height())) {
var var1 = $(window).scrollTop(),
var2 = $("#end").offset().top,
var3 = $(window).height();
var calculateOffset = (var2 - var3) - var1;
$("#wannabeSticky").css("top", "calc(50% + " + calculateOffset + "px)");
}
else {
$("#wannabeSticky").css("top", "50%");
}
});
});
For the sticky-ness to start, I took the reference point (which is the non-moving element right next to it) and its height. The sticky element gets a fixed position as long as the scrollbar goes past the reference point's center.
As the stick element is centered, it gets additional top offset values when the end of its container is reached. It is still fixed, but its top property's value takes the scroll difference, thus slowly depicting it towards the end of the container.
I don't know if this is the most elegant, straightforward, or easy to implement/understand solution, but it worked for me.
I'm updating a table header and its first column positions programatically based on how the user scrolls around to keep them aligned.
The issue I'm experiencing is that as soon as my data sets gets big enough, the scrolling gets more and more choppy/less smooth.
The relevant code is at the very bottom of the fiddle:
iScroll.on('scroll', function(){
var pos = $('#scroller').position();
$('#pos').text('pos.left=' + pos.left + ' pos.top=' + pos.top);
// code to hold first row and first column
$('#scroller th:nth-child(1)').css({top: (-pos.top), left: (-pos.left), position:'relative'});
$('#scroller th:nth-child(n+1)').css({top: (-pos.top), position:'relative'});
// this seems to be the most expensive operation:
$('#scroller td:nth-child(1)').css({left: (-pos.left), position:'relative'});
});
I know that this can be written a lot more efficent by caching the elements and so on. For example, I have tried saving the elements in to an array and updating their position in a more "vanilla" fashion:
headerElements[i].style.left = left + 'px'; // etc...
No matter how fast I make the callback, I'm still not happy about the result. Do you have any suggestions?
https://jsfiddle.net/0qv1kjac/16/
Just use ClusterizeJS! It can handle hundreds of thousands of rows and was built exactly for this purpose.
How does it work, you ask?
The main idea is not to pollute DOM with all used tags. Instead of that - it splits the list to clusters, then shows elements for current scroll position and adds extra rows to top and bottom of the list to emulate full height of table so that browser shows scrollbar as for full list
To be able to handle big amounts of data you need data virtualization. It has some restrictions, though.
First you need to decide the size of a view port. Let's say you want to render 10 items in a row and 20 items in column. It would be 10x20 items then. In you fiddle it's div with id wrapper.
Then you need to know total amount of data you have. From your fiddle it would be 100x100 items. And, also you need to know height and width of a item (cell). Let's take 40x120 (in px).
So div#wrapper is a view port, it should have fixed sized like 10x20 items. Then you need to set up correct width and height for table. The height of table would be equal to total amount of data in column including head by item height. Width for table would be total amount of items in single row by item width.
Once you set up these, div#wrapper will receive horizontal and vertical scrolls. Now you able to scroll left and bottom, but it will be just empty space. However this empty space is able to hold exact amount of data you have.
Then you need to take scroll data left and top (position), which comes in pixels and normalize it to amount of items, so you could know not how many pixels you've scrolled, but how many items you've scrolled(or rows if we scroll from top to bottom).
It could be done by division of pixels scrolled on item height. For example, you scrolled to left by 80px, that's 2 items. It means these items should be invisible because you've scrolled past them. So you know that you scrolled past 2 items, and you know that you should see 10 items in a row. That means you take your data array which has data for row with 100 items, and slice it like this:
var visibleItems = rowData.slice(itemsScrolled, itemsScrolled + 10);
It will give you items which should be visible in viewport at current scroll position. Once you have these items you need to construct html and append it to table.
Also on each scroll event you need to set top and left position for tbody and thead so they would move with scroll, otherwise you will have your data, but it will be at (0; 0) inside a viewport.
Anyway, code speaks thousand of words, so here's the fiddle: https://jsfiddle.net/Ldfjrg81/9/
Note, that this approach requires heights and widths to be precise, otherwise it will work incorrectly. Also if you have items of different sizes, this also should be taken into consideration, so better if you have fixed and equal sizes of items. In jsfiddle, I commented out the code which forces first column to stay in place, but you can render it separately.
It's a good solution to stick to some library as suggested in comments, since it handles a lot of cases for you.
You can make rendering even faster if use react.js or vue.js
This won't be the answer your are looking for but here's my 2 cents anyway.
Javascript animation (especially given the amount that the DOM has to render) will never be as smooth as you want it. Even if you could get it smooth on your machine, chances are that it will vary drastically on other peoples (Older PC's, Browsers etc).
I would see 2 options if I were to tackle this myself.
Go old school and add a horizontal and vertical scrollbar. I know it's not a pretty solution but it would work well.
Only render a certain amount of rows and discard those off screen. This could be a bit complicated but in essence you would render say 10 rows. Once the user scrolls to a point where the 11th should be there, render that one and remove the 1st. You would pop them in and out as needed.
In terms of the actual JS (you mentioned putting elements in to an array), that isn't going to help. The actual choppyness is due to the browser needing to render that many elements in the first place.
You're experiencing choppy / non-smooth scrolling because the scroll event fires at a very high pace.
And every time it fires you're adjusting the position of many elements: this is expensive and furthermore until the browser has completed the repaint it's unresponsive (here the choppy scrolling).
I see two options:
Option number one: display only the visible subset of the whole data set (this has been already suggested in another answer so I won't go futher)
Option number two (easier)
First, let animations on left and top css changes occurr via transitions. This is more efficient, is non-blocking and often let the browser take advantage of the gpu
Then instead of repeteadly adjust left and top, do it once a while; for example 0.5 seconds. This is done by the function ScrollWorker() (see code below) that recalls itself via a setTimeout().
Finally use the callback invoked by the scroll event to keep the #scroller position (stored in a variable) updated.
// Position of the `#scroller` element
// (I used two globals that may pollute the global namespace
// that piece of code is just for explanation purpose)
var oldPosition,
newPosition;
// Use transition to perform animations
// You may set this in the stylesheet
$('th').css( { 'transition': 'left 0.5s, top 0.5s' } );
$('td').css( { 'transition': 'left 0.5s, top 0.5s' } );
// Save the initial position
newPosition = $('#scroller').position();
oldPosition = $('#scroller').position();
// Upon scroll just set the position value
iScroll.on('scroll', function() {
newPosition = $('#scroller').position();
} );
// Start the scroll worker
ScrollWorker();
function ScrollWorker() {
// Adjust the layout if position changed (your original code)
if( newPosition.left != oldPosition.left || newPosition.top != oldPosition.top ) {
$('#scroller th:nth-child(1)').css({top: (-newPosition.top), left: (-newPosition.left), position:'relative'});
$('#scroller th:nth-child(n+1)').css({top: (-newPosition.top), position:'relative'});
$('#scroller td:nth-child(1)').css({left: (-newPosition.left), position:'relative'});
// Update the stored position
oldPosition.left = newPosition.left;
oldPosition.top = newPosition.top;
// Let animation complete then check again
// You may adjust the timer value
// The timer value must be higher or equal the transition time
setTimeout( ScrollWorker, 500 );
} else {
// No changes
// Check again after just 0.1secs
setTimeout( ScrollWorker, 100 );
}
}
Here is the Fiddle
I set the Worker pace and the transition time to 0.5 secs. You may adjust the value with higher or lower timing, eventually in a dinamic way based on the number of elements in the table.
Yes! Here are some improvements to the code from your JS Fiddle. You can view my edits at: https://jsfiddle.net/briankueck/u63maywa/
Some suggested improvements are:
Switching position:relative values in the JS layer to position:fixed in the CSS layer.
Shortening the jQuery DOM chains, so that the code doesn't start at the root element & walk all the way through the dom with each $ lookup. The scroller is now the root element. Everything uses .find() off of that element, which creates shorter trees & jQuery can traverse those branches faster.
Moving the logging code out of the DOM & into the console.log. I've added a debugging switch to disable it, as you're looking for the fastest scrolling on the table. If it runs fast enough for you, then you can always re-enable it to see it in the JSFiddle. If you really need to see that on the iPhone, then it can be added into the DOM. Although, it's probably not necessary to see the left & top position values in the iPhone.
Remove all extraneous $ values, which aren't mapped to the jQuery object. Something like $scroller gets confusing with $, as the latter is the jQuery library, but the former isn't.
Switching to ES6 syntax, by using let instead of var will make your code look more modern.
There is a new left calculation in the <th> tag, which you'll want to look at.
The iScroll event listener has been cleaned up. With position:fixed, the top <th> tags only need to have the top property applied to them. The left <td> tags only need to have the left property applied to them. The corner <th> needs to have both the top & left property applied to it.
Remove everything that's unnecessary, like the extraneous HTML tags which were used for logging purposes.
If you really want to go more vanilla, change out the .css() methods for the actual .style.left= -pos.left + 'px'; and .style.top= -pos.top + 'px'; properties in the JS code.
Try using a diff tool like WinMerge or Beyond Compare to compare the code from your version to what's in my edits, so that you can easily see the differences.
Hopefully, this will make the scrolling smoother, as the scroll event doesn't have to process anything that it doesn't need to do... like 5 full DOM traversing look-ups, rather than 3 short-tree searches.
Enjoy! :)
HTML:
<body>
<div id="wrapper">
<table id="scroller">
<thead>
</thead>
<tbody>
</tbody>
</table>
</div>
</body>
CSS:
/* ... only the relevant bits ... */
thead th {
background-color: #99a;
min-width: 120px;
height: 32px;
border: 1px solid #222;
position: fixed; /* New */
z-index: 9;
}
thead th:nth-child(1) {/*first cell in the header*/
border-left: 1px solid #222; /* New: Border fix */
border-right: 2px solid #222; /* New: Border fix */
position: fixed; /* New */
display: block; /*seperates the first cell in the header from the header*/
background-color: #88b;
z-index: 10;
}
JS:
// main code
let debug = false;
$(function(){
let scroller = $('#scroller');
let top = $('<tr/>');
for (var i = 0; i < 100; i++) {
let left = (i === 0) ? 0 : 1;
top.append('<th style="left:' + ((123*i)+left) + 'px;">'+ Math.random().toString(36).substring(7) +'</th>');
}
scroller.find('thead').append(top);
for (let i = 0; i < 100; i++) {
let row = $('<tr/>');
for (let j = 0; j < 100; j++) {
row.append('<td>'+ Math.random().toString(36).substring(7) +'</td>');
}
scroller.find('tbody').append(row);
}
if (debug) console.log('initialize iscroll');
let iScroll = null;
try {
iScroll = new IScroll('#wrapper', {
interactiveScrollbars: true,
scrollbars: true,
scrollX: true,
probeType: 3,
useTransition:false,
bounce:false
});
} catch(e) {
if (debug) console.error(e.name + ":" + e.message + "\n" + e.stack);
}
if (debug) console.log('initialized');
iScroll.on('scroll', function(){
let pos = scroller.position();
if (debug) console.log('pos.left=' + pos.left + ' pos.top=' + pos.top);
// code to hold first row and first column
scroller.find('th').css({top:-pos.top}); // Top Row
scroller.find('th:nth-child(1)').css({left:-pos.left}); // Corner
scroller.find('td:nth-child(1)').css({left:-pos.left}); // 1st Left Column
});
});
Is it necessary that you create your own scroller? Why don't you just style the data in HTML/CSS and just use the overflow attribute? JavaScript needs work on it's ability to adjust framerates. I was using your jFiddle earlier and it worked just fine with the native overflow handler.
Found this in the manual. Probably not what you wanna hear but it's the way it is:
IScroll is a class that needs to be initiated for each scrolling area. There's no limit to the number of iScrolls you can have in each page if not that imposed by the device CPU/Memory.
Try to keep the DOM as simple as possible. iScroll uses the hardware compositing layer but there's a limit to the elements the hardware can handle.
The reason the performance degradation is happening is that your scroll event handler is firing again and again and again instead of waiting for a reasonable and imperceptible interval.
The screenshot shows what happened when I tracked how many times the event handler fired, while scrolling for just a few seconds. The computationally-heavy event handler was fired over 600 times!!! This is more than 60 times per second!!!
It may seem counter-intuitive, but reducing the frequency that the table is updated will vastly increase perceived response times. If your user scrolls for fraction of a second, about 150 milliseconds, and the table is updated ten times, freezing the display during the scrolling, the net result is far worse than if the table were updated only three times and moved fluidly rather than freezing. It is just wasted processor burn to update more times than the browser can handle without freezing.
So, how do you make an event handler that fires at a maximum frequency, for example 25 times per second, even it is triggered much more often, like 100 times per second?
The naive way of doing it is to run a setInterval event. That is better, but horribly inefficient as well. There is a better way of doing it, by setting a delayed event handler, and clearing it on subsequent invocations before setting it again, until the minimum time interval has passed. This way it only runs no more often than at the maximum desired frequency. This is one major case for why the ``clearInterval'' method was invented.
Here is live working code:
https://jsfiddle.net/pgjvf7pb/7/
Note: when refreshing continuously like this, the header column may appear out of position.
I advise to do the update only when the scrolling has paused for about 25ms or so, rather than continuously. This way, it appears to the user that the header column is dynamically calculated as well as being fixed in place, because it appears instantly after scrolling rather than seeming to scroll with the data.
https://jsfiddle.net/5vcqv7nq/2/
The logic is like this:
variables outside your event handler
// stores the scrolling operation for a tiny delay to prevent redundancy
var fresh;
// stores time of last scrolling refresh
var lastfresh = new Date();
operations inside your event handler
// clears redundant scrolling operations before they are applied
if (fresh) clearTimeout(fresh);
var x = function() {
// stores new time of scrolling refresh
lastfresh = new Date();
// perform scrolling update operations here...
};
// refresh instantly if it is more than 50ms out of date
if (new Date() - lastfresh > 50) x();
// otherwise, pause for half of that time to avoid wasted runs
else fresh = setTimeout(x, 25);
Demo: https://jsfiddle.net/pgjvf7pb/7/
Once again, I recommend that you remove the line of code that refreshes the data instantly, and the else condition after that, and simply use one line
fresh = setTimeout(x, 25);
This will appear to instantly calculate the header column the moment any scrolling is finished, and saves even more operations. My second link to JS Fiddle shows what this looks like, here: https://jsfiddle.net/5vcqv7nq/2/
I've recently taken over work on a friend's website, here. I want to get the small logo above the description box to only show up once the user has scrolled past (and subsequently hidden) the large header at top, and disappear again if the user scrolls back up past it. I've tried the methods recommended in these other posts here and here, which seem like the same basic idea but I can't get any of them to work.
I'm new to anything and everything scripting (which I'm entirely sure is the biggest problem here, I know.) So any help is appreciated as what I'm apparently doing wrong.
Start by giving the <div class="fixeddiv"> a style="display: none". Then add the following (since you're already using jQuery):
$(document).ready(function () {
var contentOffset = getOffset();
function getOffset() {
var allOffsets = $("div#content").offset();
return allOffsets.top;
}
$(window).resize(function () {
contentOffset = getOffset();
});
$(window).scroll(function () {
var windowTop = $(window).scrollTop();
if (windowTop > contentOffset) {
$("div.fixeddiv").show();
} else {
$("div.fixeddiv").hide();
}
});
});
Here's what this code does. When the document is done loading, it gets the number of pixels that the "content" div is from the top of the document (offset). It does this again any time the window is resized. Then, when someone scrolls up or down, it gets the number of pixels that are already hidden above the scroll (scrollTop). If the number of hidden pixels is greater than the offset of the #content div from the top of the window, that means we've scrolled past the top of the content div and should show the icon. Otherwise, we should hide the icon.
Ok - here is what I am trying to do. I was looking online for a cool timeline that I can purchase - allowing zoom in zoom out, posting of events on it, and so on. However, all the examples I found are either too expensive or just downright useless.
So, I have decided to create my own, but there are two elements that I am having trouble with.
1) Converting the wheel scroll to left-right scrolling (so not up-down). I can't seem to find an easy and quick way to do this.
But, more importantly..
2) I need the area I will be showing the timeline on to automatically expand as I go about my scrolling. So, if I scroll down, it will add an "equivalent" area on the right, and down, on the left. So I was thinking like making an iFrame (already use these) and when you scroll it just adds more "timeline" on the left or the right, loads what ever it needs to load from the DB/list of events, and so on, ad infinitum, thus creating an ever-expanding list of blocks that are time-sized.
If I can do the two things above, then I am set - the rest (loading/positioning) I can figure out - just these two things are eluding my imagination and ability to find an answer.
Basically you need a horizontal infinite scroll script.
Take this plugin I wrote:
$.fn.hScroll = function( options )
{
function scroll( obj, e )
{
var evt = e.originalEvent;
var direction = evt.detail ? evt.detail * (-120) : evt.wheelDelta;
if( direction > 0)
{
direction = $(obj).scrollLeft() - 120;
}
else
{
direction = $(obj).scrollLeft() + 120;
}
$(obj).scrollLeft( direction );
e.preventDefault();
}
$(this).width( $(this).find('div').width() );
$(this).bind('DOMMouseScroll mousewheel', function( e )
{
scroll( this, e );
});
}
Initialize it with:
$('body').hScroll();
Makes your website a horizontally scrollable website.
Your content div must be wider than your body (ex. 3000px).
As for the infinite scrolling effect you pretty much gotta do that your self because I can't know what kind of data you'll input. But I'll explain.
Your children elements in the content div must be floated to left. (every new appended div will not go to new line).
Set an interval to check if the user's scrollLeft position is near the end of the content (just like pinterest and similar site).
function loadNewData(){ /* Your search for data and update here. */ }
setInterval('loadNewData', 500);
search for new data according to your last one with AJAX. When you get new data, append it into your content div (in a div that's floated left, as I wrote previously), and mark it as your last item.
Maybe you could use your ID to mark the last item on it's div.
<div data-id="467" class="item"> // your data here </div>
You can fetch it with
$('.item:last').attr('data-id');
with jQuery.
I am looking for advice on how to create an autoscrolling effect using jQuery which would enable an entire div within a page to begin scrolling vertically upon loading at a constant slow speed. This would be a div with a large amount of content of which only a small amount was visible on the screen at any one time.
The scroll needs to be automatic, smooth and at a defined rate for example 10 pixels per second. Additionally when the scroll gets to the bottom of the page I need to be able to call a function.
I have tried a few different jQuery plugins but found nothing yet that worked reliably. Can anybody suggest an approach to take here?
Thanks
Simon
This can easily be done without jquery.
function init() {
var div = document.getElementById("myDiv");
// increase the scroll position by 10 px every 10th of a second
setInterval(function() {
// make sure it's not at the bottom
if (div.scrollTop < div.scrollHeight - div.clientHeight)
div.scrollTop += 10; // move down
}, 100); // 100 milliseconds
}
Try this technique
try this plugin : scrollTo
especially the onAfter