Develop Reference

fast smooth scroll on mouse wheel

I have a project in which I want fast smooth scrolling. I tried lot and I find some solutions. But they all can't scroll smooth when I rotate mouse wheel multiple times at a time and the last rotate of mouse wheel get smooth. After tons of searching I got a example of what i want. But I can't figure out what's is the js function. Here is the example. I don't want to use any plugin because I already used too many plugins in my project and for this it's loads so slow. Is it possible with only Jquery or pure javascript?

It's not my solution but I thought it's fitting and pretty neat so I will just copy-paste it:
jQuery.extend(jQuery.easing, {
easeOutQuint: function(x, t, b, c, d) {
return c * ((t = t / d - 1) * t * t * t * t + 1) + b;
}
});
var wheel = false,
$docH = $(document).height() - $(window).height(),
$scrollTop = $(window).scrollTop();
$(window).bind('scroll', function() {
if (wheel === false) {
$scrollTop = $(this).scrollTop();
}
});
$(document).bind('DOMMouseScroll mousewheel', function(e, delta) {
delta = delta || -e.originalEvent.detail / 3 ||
e.originalEvent.wheelDelta / 5; //edit this to your needs - the higher the slower
wheel = true;
$scrollTop = Math.min($docH, Math.max(0, parseInt($scrollTop - delta * 30)));
$($.browser.webkit ? 'body' : 'html').stop().animate({
scrollTop: $scrollTop + 'px'
}, 2000, 'easeOutQuint', function() {
wheel = false;
});
return false;
});
This overwrites the default behaviour for scroll events.
Source and full credits to Fiddle User Szar - fiddle: https://jsfiddle.net/Szar/xmkwa8ft/
P.S. this was found in a 1min google search using the term "smooth mouse scroll css"

Link clicked first time - on scroll animation doesn't work

Issue:
When I click the skill-set link for the first time, the animation occurs but does not occur when you scroll down. Each circle is to start it's own animation when the user scrolls down the page. If you click the skill-set link twice though, everything works as its supposed to.
So my question at hand is, why doesn't the animation on scroll occur on the first time the skill-set link is clicked?
Here is a DEMO of what I am talking about, please excuse the terrible layout. Once you click on the skill-set link, you see the animation happen, but when you scroll down, the animation is already completed...However, if you click the skill-set link twice, and then scroll down, you see each circle animate when you scroll down. This is what should happen on the first time the link is clicked, but for some odd reason it isn't.
JS:
$('#skill-set-link').click(function () {
function animateElements(index, element) { // (e, init)
if (element) { // (init)
$('.progressbar').data('animate', false);
}
$('.progressbar').each(function () {
var elementPos = $(this).offset().top;
var topOfWindow = $(window).scrollTop();
var percent = $(this).find('.circle').attr('data-percent');
var percentage = parseInt(percent, 10) / parseInt(100, 10);
var animate = $(this).data('animate');
if (elementPos < topOfWindow + $(window).height() + 10 && !animate) {
$(this).data('animate', true);
$(this).find('.circle').circleProgress({
startAngle: -Math.PI / 2,
value: percent / 100,
thickness: 2, // Change this for thickness
fill: {
color: '#16A085'
}
}).on('circle-animation-progress', function (event, progress, stepValue) {
$(this).find('.percent').text((stepValue * 100).toFixed(0) + "%"); // NOTE: Change '.toFixed(0)' to '.toFixed(1)' to get 1 decimal place to the right...
}).stop();
}
});
}
animateElements({}, true);
$('.about_body_wrapper').scroll(animateElements);
});
=========================================================================
Any idea as to why the animation on scroll doesn't occur the first time the link is clicked?

The behavior is occurring because everything in the skill-set-link DIV is still hidden when it runs the first time, so the top position of all of the progressbar elements is zero. Since they are zero, they are meeting the criteria of the if statement and the animation is being enabled on all of them.
To fix it, I added a call to show() the progressbar elements, including the parameter to run animateElements when show() is complete.
I moved the call to set "animate" to false to the menu item click function as it didn't really serve any purpose in animateElements. I also removed the animateElements function from the click event handler to simplify reading the code.
function animateElements(index, element) { // (e, init)
$('.progressbar').each(function () {
var elementPos = $(this).offset().top;
var topOfWindow = $(window).scrollTop();
var percent = $(this).find('.circle').attr('data-percent');
var percentage = parseInt(percent, 10) / parseInt(100, 10);
var animate = $(this).data('animate');
if (elementPos < topOfWindow + $(window).height() + 10 && !animate) {
$(this).data('animate', true);
$(this).find('.circle').circleProgress({
startAngle: -Math.PI / 2,
value: percent / 100,
thickness: 2, // Change this for thickness
fill: {
color: '#16A085'
}
}).on('circle-animation-progress', function (event, progress, stepValue) {
$(this).find('.percent').text((stepValue * 100).toFixed(0) + "%"); // NOTE: Change '.toFixed(0)' to '.toFixed(1)' to get 1 decimal place to the right...
}).stop();
}
});
}
$('#skill-set-link').click(function () {
$('.progressbar').data('animate', false);
$('#skill-set').fadeIn(animateElements);
});
$(window).scroll(animateElements);

Thanks to the help from Tony Hinkle - Here is the answer.
Due to the main div being hidden - we needed to show() the main div beforehand...However, adding $('#skill-set').show(0, animateElements); as suggested by Tony, didn't quite work right - so instead $('#skill-set').fadeIn(animateElements) replaced that along with taking out the 0 which seemed to do the trick.
Many thanks to Tony though for steering me in the right direction!
Here is the final snippet used to make this work as desired:
function animateElements(index, element) { // (e, init)
$('.progressbar').each(function () {
var elementPos = $(this).offset().top;
var topOfWindow = $(window).scrollTop();
var percent = $(this).find('.circle').attr('data-percent');
var percentage = parseInt(percent, 10) / parseInt(100, 10);
var animate = $(this).data('animate');
if (elementPos < topOfWindow + $(window).height() + 10 && !animate) {
$(this).data('animate', true);
$(this).find('.circle').circleProgress({
startAngle: -Math.PI / 2,
value: percent / 100,
thickness: 2, // Change this for thickness
fill: {
color: '#16A085'
}
}).on('circle-animation-progress', function (event, progress, stepValue) {
$(this).find('.percent').text((stepValue * 100).toFixed(0) + "%"); // NOTE: Change '.toFixed(0)' to '.toFixed(1)' to get 1 decimal place to the right...
}).stop();
}
});
}
$('#skill-set-link').click(function () {
$('.progressbar').data('animate', false);
$('#skill-set').fadeIn(animateElements);
});
$(window).scroll(animateElements);
And here is the final iteration: DEMO
Don't mind the layout... :)

Image slider is choppy

I have put together a plain javascript/css image slider, started out as just a learning exercise but am now looking to apply it in the real world. The problem is that the animation is choppy on my desktop (which is a v. high spec gaming rig) - and even worse on a mobile (to the degree it's not really an animation anymore)
You can see it in action here:
www.chrishowie.co.uk/sands/
jsfiddle isolates much of the pertinent code - it's not a "this doesn't work" issue, so hopefully the fiddle gives enough to help optimize it.
http://jsfiddle.net/9aozrxy8/5/
In summary: I have a DIV with 4 images in a row, each image is 100% the width of the page. I use javascript to translateX (I have tried translate3d as heard this uses GPU, but didnt make much diff) and I set CSS transitions to ease-in the transform.
I also thought that potentially I am just trying to do too much on this site - but then I look at some other sites doing a heck of a lot more and it's smooth as silk. So I guess I'm missing something.
function slideRight() {
if (sliding) {
return false
};
window.sliding = true;
el = document.getElementById("slider");
cst = getComputedStyle(el);
transformst = cst.transform || cst.webkitTransform || cst.mozTransform;
widthst = cst.width;
widthst = widthst.replace("px", ""); // computed width of slider (7680px)
slidewidth = widthst / 4;
transformst = transformst.replace("matrix(", "");
transformst = transformst.replace(")", "");
transformst = transformst.split(",");
transformst = transformst[4]; // returns current transform in px without unit (px)
if (!transformst) {
transformst = 0;
}
var activebtn = "sldr" + Math.round((Number(transformst) / (-1 * slidewidth)));
document.getElementById(activebtn).classList.remove("sliderbuttonactive");
if (activebtn != "sldr3") {
document.getElementById("slider" + Math.round((2 + Number(transformst) / (-1 * slidewidth)))).style.visibility = "visible";
document.getElementById("slider" + Math.round((2 + Number(transformst) / (-1 * slidewidth)))).style.display = "initial";
document.getElementById("slider").style.transform = "translate3d(" + 25 * ((Number(transformst) / (slidewidth)) - 1) + "%, 0, 0)";
document.getElementById("slider").style.transform = "-webkit-translate3d(" + 25 * ((Number(transformst) / (slidewidth)) - 1) + "%, 0, 0)";
document.getElementById("slider").style.transform = "-moz-translate3d(" + 25 * ((Number(transformst) / (slidewidth)) - 1) + "%, 0, 0)";
document.getElementById("slider").style.transform = "-ms-translate3d(" + 25 * ((Number(transformst) / (slidewidth)) - 1) + "%, 0, 0)";
document.getElementById("leftslidebtn").style.visibility = "visible";
document.getElementById("leftslidebtn").style.display = "block";
}
activebtn = activebtn.replace("sldr", "");
activebtn = "sldr" + (1 + Number(activebtn));
document.getElementById(activebtn).classList.add("sliderbuttonactive");
if (Number(activebtn.replace("sldr", "")) == 3) {
document.getElementById("rightslidebtn").style.visibility = "hidden";
document.getElementById("rightslidebtn").style.display = "none";
}
setTimeout(function () {
window.sliding = false
}, 2000);
}
update: still not resolved but on mobile I have made it usable by reducing the image size for small screens and also not displaying images that are off-screen. Not perfectly smooth but getting there.
Thanks a lot,
C

Like Jeremy mentioned, that the "transition" in your JSFiddle caused the problem, it's also causing it on your website.
In your "Main.css" in line 221. Remove the "transition: top ease 2s;" from class .slide
Everything works fine then on Win8.1/Google Chrome/i7

jQuery script efficiency

I use the below jQuery function named textfill on hundreds of divs. Basically it resizes the inner text to fit the enclosing div such that the font-size of the text is maximum, So longer texts are smaller than shorter ones but are at maximum font size that they can be without overflowing from the div.
; (function($) {
/**
* Resizes an inner element's font so that the inner element completely fills the outer element.
* #version 0.1
* #param {Object} Options which are maxFontPixels (default=40), innerTag (default='span')
* #return All outer elements processed
* #example <div class='mybigdiv filltext'><span>My Text To Resize</span></div>
*/
$.fn.textfill = function(options) {
var defaults = {
maxFontPixels: 40,
innerTag: 'span'
};
var Opts = jQuery.extend(defaults, options);
return this.each(function() {
var fontSize = Opts.maxFontPixels;
var ourText = $(Opts.innerTag + ':visible:first', this);
var maxHeight = $(this).height();
var maxWidth = $(this).width();
var textHeight;
var textWidth;
do {
ourText.css('font-size', fontSize);
textHeight = ourText.height();
textWidth = ourText.width();
fontSize = fontSize - 1;
} while ((textHeight > maxHeight || textWidth > maxWidth) && fontSize > 3);
var pos = (maxHeight-textHeight)/2;
ourText.css('top', pos +'px');
});
};
})(jQuery);
Because I run this script on hundreds of divs that look like:
<div class="textDiv"><span>text appears here</span></div>
At the same time using:
$('.textDiv').each(function() { $(this).textfill({ maxFontPixels: 28 })});
It takes 40 to 70 seconds depending on the amount of divs. I desperately need to tune the code so it will run faster. I've tried for the last two hours but can't seem to make it run faster. Can someone help?
EDIT:
Took some input from the comments and changed the code to:
var items = document.getElementsByClassName("textDiv");
for (var i = items.length; i--;) {
$(items[i]).textfill({ maxFontPixels: 28 });
}
It seems to be a bit faster but still really slow.

$('.textDiv').each(function() { $(this).textfill({ maxFontPixels: 28 })});
You're using the function wrong. Every (proper) plugin does already work on jQuery collections, and has the each built-in so that you do not need to put it around the invocation. Just do
$('.textDiv').textfill({ maxFontPixels: 28 });
Yet I think that is not your actual problem; loops are quite fast and even for hundred items it won't take seconds. The problem is
ourText.css('font-size', fontSize);
textHeight = ourText.height();
textWidth = ourText.width();
inside a loop (actually in two nested loops), as it requires a complete reflow by the browser. You will need to minimize the calls to this part, for example by using some kind of binary search (bisection) and/or by applying a interpolation metric that approximates the font size (number of characters divided by area for example?) to get a good starting value.
Beside that, there might be other minor optimisations:
cache $(this)
$(Opts.innerTag + ':visible:first', this); looks like a quite complex selector. Is that really necessary, do you expect hidden elements? Move such extras to the options, and go with $(this).children().first() by default.
I'm not sure about your CSS, but how do you set the dimensions of your divs (which you retrieve as maxHeight/maxWidth)? For reducing the reflow costs when changing the fontsize inside, an additional overflow:hidden can help.

Obviously the bottle neck is the inner-most looping (the next is parent of inner-most and so on).
Why don't use "bisection" for finding out the font size?:
For 200 divs:
Bisect solution (needs some refactoring):
http://jsfiddle.net/nx2n2/8/
Time: ~700
Current solution:
http://jsfiddle.net/pXL5z/3/
Time: ~1400
The most important code:
var change = Math.ceil(fontSize / 2);
while(true) {
change = Math.ceil(change / 2);
var prev = fontSize;
do {
fontSize = fontSize - change;
ourText.css('font-size', fontSize);
textHeight = ourText.height();
textWidth = ourText.width();
} while ((textHeight > maxHeight || textWidth > maxWidth) && fontSize > 3);
change = Math.ceil(change / 2);
while (textHeight < maxHeight && textWidth < maxWidth) {
fontSize = fontSize + change;
ourText.css('font-size', fontSize);
textHeight = ourText.height();
textWidth = ourText.width();
}
var current = fontSize;
if(prev == current) {
break;
}
}
// this is because you subtract after change in your original solution
// only for 'compatibility' with original solution
fontSize = fontSize - 1;

iScroll Scrolling Past Bottom?

You can easily see the problem on the first page here: http://m.vancouverislandlife.com/
Scroll down (slide up) and allow the content to leave the page, and it doesn't bounce back and is lost forever. However, on pages whose content does overflow the page and is therefore supposed to be scrollable, the scrolling works correctly (see Accomodations > b&b's and scroll down for an example of this).
I noticed that on my computer, the scrolling on the first page is always stuck at -899px. I can't find anybody else who's experienced this problem and no matter what I try, I just can't fix it! Help!
(It's not exactly urgent, however, as the target audience of iPhones and iPod Touches aren't affected by this since they have so little screen room.)
Okay, new problem. To solve the iScroll issue, I just created a custom script. However, it's not working correctly on the actual device. On desktop browsers, it works just fine. On mobile, it occasionally jumps back to the top and won't recognize some touches. This is probably because of the way I cancelled the default event and had to resort to a bit of a hack. How can I fix this? (Yup - simple problem for a +500 bounty. Not bad, huh?)
Here's the script, and the website is at the usual place:
function Scroller(content) {
function range(variable, min, max) {
if(variable < min) return min > max ? max : min;
if(variable > max) return max;
return variable;
}
function getFirstElementChild(element) {
element = element.firstChild;
while(element && element.nodeType !== 1) {
element = element.nextSibling;
}
return element;
}
var isScrolling = false;
var mouseY = 0;
var cScroll = 0;
var momentum = 0;
if("createTouch" in document) {
content.addEventListener('touchstart', function(evt) {
isScrolling = true;
mouseY = evt.pageY;
evt.preventDefault();
}, false);
content.addEventListener('touchmove', function(evt) {
if(isScrolling) {
evt = evt.touches[0];
var dY = evt.pageY - mouseY;
mouseY = evt.pageY;
cScroll += dY;
momentum = range(momentum + dY * Scroller.ACCELERATION, -Scroller.MAX_MOMENTUM, Scroller.MAX_MOMENTUM);
var firstElementChild = getFirstElementChild(content);
content.style.WebkitTransform = 'translateY(' + range(cScroll, -(firstElementChild.scrollHeight - content.offsetHeight), 0).toString() + 'px)';
}
}, false);
window.addEventListener('touchend', function(evt) {
isScrolling = false;
}, false);
} else {
content.addEventListener('mousedown', function(evt) {
isScrolling = true;
mouseY = evt.pageY;
}, false);
content.addEventListener('mousemove', function(evt) {
if(isScrolling) {
var dY = evt.pageY - mouseY;
mouseY = evt.pageY;
cScroll += dY;
momentum = range(momentum + dY * Scroller.ACCELERATION, -Scroller.MAX_MOMENTUM, Scroller.MAX_MOMENTUM);
var firstElementChild = getFirstElementChild(content);
content.style.WebkitTransform = 'translateY(' + range(cScroll, -(firstElementChild.scrollHeight - content.offsetHeight), 0).toString() + 'px)';
}
}, false);
window.addEventListener('mouseup', function(evt) {
isScrolling = false;
}, false);
}
function scrollToTop() {
cScroll = 0;
content.style.WebkitTransform = '';
}
function performAnimations() {
if(!isScrolling) {
var firstElementChild = getFirstElementChild(content);
cScroll = range(cScroll + momentum, -(firstElementChild.scrollHeight - content.offsetHeight), 0);
content.style.WebkitTransform = 'translateY(' + range(cScroll, -(firstElementChild.scrollHeight - content.offsetHeight), 0).toString() + 'px)';
momentum *= Scroller.FRICTION;
}
}
return {
scrollToTop: scrollToTop,
animationId: setInterval(performAnimations, 33)
}
}
Scroller.MAX_MOMENTUM = 100;
Scroller.ACCELERATION = 1;
Scroller.FRICTION = 0.8;

I think Andrew was on the right track with regards to setting the height of the #wrapper div. As he pointed out that,
that.maxScrollY = that.wrapperH - that.scrollerH;
Normally, this would work. But now that you've changed your #content to position: fixed, the wrapper element is no longer "wrapping" your content, thus that.wrapperH has a value of 0, things break.
Disclaimer: I did not go through the entire script so I may be wrong here
When manually setting a height to #wrapper, say 500px, it becomes,
that.maxScrollY = 500 - that.scrollerH;
The folly here is that when there's a lot of content and the window is small, that.scrollerH is relatively close in value to 500, say 700px. The difference of the two would be 200px, so you can only scroll 200 pixels, thus giving the appearance that it is frozen. This boils down to how you set that maxScrollY value.
Solution (for Chrome browser at least):
Since #wrapper effectively contains no content, we cannot use it in the calculations. Now we are left with the only thing that we can reliably get these dimensions from, #content. In this particular case, it appears that using the content element's scrollHeight yield what we want. This is most likely the one that has the expected behavior,
that.maxScrollY = that.scrollerH - that.scroller.scrollHeight;
scrollerH is the offsetHeight, which is roughly the height of what you see in the window. scroller.scrollHeight is the height that's considered scrollable. When the content does not exceed the length of the page, they are roughly equivalent to one another. That means no scroll. When there are a lot of content, the difference of these two values is the amount of scroll you need.
There is still a minor bug, and this looks like it's already there. When you have a lot of content, the last few elements are covered up by the bar when scrolled to the bottom. To fix this, you can set an offset such as,
that.maxScrollY = that.scrollerH - that.scroller.scrollHeight - 75;
The number 75 arbitrary. It's probably best if it's the height of the bar itself with 2 or 3 pixels for a bit of padding. Good luck!
Edit:
I forgot to mention last night, but here are the two sample pages that I used in trying to debug this problem.
Long page
Short page

This may be a CSS issue. In your stylesheet (mobile.css line 22), try removing position:fixed from #content.
That should allow the document to scroll normally (vertical scrollbar on a computer, "slideable" on a mobile browser).
Elements with position:fixed exit the normal flow of the document, their positioning is relative to the browser window. This is probably why you're having issues with scrolling. Fixed positioning is generally for elements which should always remain in the same place, even when the page is scrolled (ie. a notification bar "pinned" at the top of a page).

No definite solution, but more a direction I'd go for:
#wrapper and #content's overflow:hidden paired #content's postion:fixed and seem to be the cause of the issue.
If position: fixed is removed from #content, scrolling is possible but the "blank" divs are wrongly layered (tested in Firefox 5).

Your wrapper div seems to have a height of 0. So all the calculations are negative, setting it's height to the window height will correct the scroll issue. When I manually set the wrappers height via firebug and chromes debug bar the scroll functions as it should.
You #content div seems to have its size change on resize, probably a better idea to have the #wrapper div have its size change and then have #content inherit the size.
[Edit]
You don't believe me so codez, From iscroll-lite.js
refresh: function () {
var that = this,
offset;
that.wrapperW = that.wrapper.clientWidth;
that.wrapperH = that.wrapper.clientHeight;
that.scrollerW = that.scroller.offsetWidth;
that.scrollerH = that.scroller.offsetHeight;
that.maxScrollX = that.wrapperW - that.scrollerW;
that.maxScrollY = that.wrapperH - that.scrollerH;
In your page that translates to,
that.wrapperH = 0;
that.maxScrollY = -that.scrollerH
When a scroll finishes, this code gets called.
var that = this,
resetX = that.x >= 0 ? 0 : that.x < that.maxScrollX ? that.maxScrollX : that.x,
resetY = that.y >= 0 || that.maxScrollY > 0 ? 0 : that.y < that.maxScrollY ? that.maxScrollY : that.y;
...
that.scrollTo(resetX, resetY, time || 0);
See that that.maxScrollY > 0 ? ? If maxScrollY is negative then scrolling up will never bounce back.

I ended up just making my own, small script to handle the scrolling:
// A custom scroller
function range(variable, min, max) {
if(variable < min) return min > max ? max : min;
if(variable > max) return max;
return variable;
}
var isScrolling = false;
var mouseY = 0;
var cScroll = 0;
if("createTouch" in document) {
// TODO: Add for mobile browsers
} else {
content.addEventListener('mousedown', function(evt) {
isScrolling = true;
mouseY = evt.pageY;
}, false);
content.addEventListener('mousemove', function(evt) {
if(isScrolling) {
var dY = evt.pageY - mouseY;
mouseY = evt.pageY;
cScroll += dY;
var firstElementChild = content.getElementsByTagName("*")[0];
content.style.WebkitTransform = 'translateY(' + range(cScroll, -(firstElementChild.scrollHeight - content.offsetHeight), 0).toString() + 'px)';
}
}, false);
window.addEventListener('mouseup', function(evt) {
isScrolling = false;
}, false);
}
and modifying a few other parts. It does save a lot of download time, I suppose, also.
I'm still going to accept answers and award the bounty in 5 days, though.

Changed question warrants a new answer. I took a look at the code and I saw that you calculated the momentum on each step of the "move" function. This does not make sense because the momentum is used after the move has ended. What this meant was to capture the mouse position at the beginning, and then calculate the difference at the end. So I added two new variables,
var startTime;
var startY;
Inside the start event (mousedown/touchstart), I added,
startY = evt.pageY;
startTime = evt.timeStamp || Date.now();
Then I have the following for my end handler,
var duration = (evt.timeStamp || Date.now()) - startTime;
if (duration < 300) {
var dY = evt.pageY - startY;
momentum = range(momentum + dY * Scroller.ACCELERATION, -Scroller.MAX_MOMENTUM, Scroller.MAX_MOMENTUM);
} else {
momentum = 0;
}
I also removed the momentum calculation from inside of mousemove/touchmove. Doing this removed the jumping around behavior that I was seeing on my iPhone. I am seeing other unwanted behaviors as well (the whole window "scrolls"), but I'm guessing that you've been working to get rid of those so I didn't attempt.
Good luck. Here's a coded up page that I duplicated for my testing. I also took the liberty to refactor the code for this section to remove some duplicated code. It's under mobile3.js if you want to look at it.