Why does smooth scrollBy only work first time? - javascript

I am using the following code on a website to imitate smooth scrolling:
function scrollWindow() {
// window.scrollBy(1040,0)
var timerID = setInterval(function() {
window.scrollBy(104, 0);
if( window.pageXOffset >= 1040 ) clearInterval(timerID);
}, 10);
}
However, after clicking Scroll (the scrollWindow function) the page scrolls 1040 like it should.
Any subsequent time, it does not work, unless i manually scroll back to the beginning.
Would i be right in thinking that if( window.pageXOffset >= 1040 ) is canceling it because although it hasn't moved 1040, it is past that point on the page?
If so, how can i solve this?

Yes, your assessment is correct; but it could be corrected with a twist in the approach:
function scrollWindow() {
var scrolledSoFar = 0;
var scrollStep = 104;
var scrollEnd = 1040;
var timerID = setInterval(function() {
window.scrollBy(scrollStep, 0);
scrolledSoFar += scrollStep;
if( scrolledSoFar >= scrollEnd ) clearInterval(timerID);
}, 10);
}
Update
Another pitfall in the code is that you are executing scrollBy before checking for the condition. So on your page, even after you have scrolled past 1040, clicking scroll will move the page by one scrollStep amount. To prevent that, this order is better:
function scrollWindow() {
var scrolledSoFar = 0;
var scrollStep = 104;
var scrollEnd = 1040;
var timerID = setInterval(function() {
if( scrolledSoFar < scrollEnd ) {
window.scrollBy(scrollStep, 0);
scrolledSoFar += scrollStep;
} else {
clearInterval(timerID);
}
}, 10);
}

Related

Detect if user scrolls more than 20px no matter where it's on the page

Is it possible to detect if the user scrolls more than 20px wherever it's on the page??
I mean, in a one page design, I need to remove a class when the user scrolls more than 20px but not only from the top of the document.
Each time he opens a popup, a class is added to the popup in question, once the user scrolls, I would like to remove this class.
Repeat this function no matter where it's on the page.
My current code :
$(window , 'body').on('scroll', function() {
$('.navbar-collapse').collapse('hide');
$("#wrapper").removeClass('newsletter-opened');
$("#newsletter").removeClass('opened');
});
Thank you!
You can use jQuery for that.
With my solution, if user has scroll 200px when he come on your page if he scroll to top or bottom with minumum 20px of scroll your changes was called.
var userScroll = $(document).scrollTop();
$(window).on('scroll', function() {
var newScroll = $(document).scrollTop();
if(userScroll - newScroll > 20 || newScroll - userScroll > 20){
$('.navbar-collapse').collapse('hide');
$("#wrapper").removeClass('newsletter-opened');
$("#newsletter").removeClass('opened');
}
}
EDIT:
After look your jsFiddle, i know what you want, just check that :
Just define the scroll at the moment when popin is enable and make your job only when the popin has class opened
$(document).ready(function(){
$("a.open-newsletter").on( "click", function() {
$("#newsletter").toggleClass('opened');
userScroll = $(document).scrollTop();
return false;
});
$(window , 'body').on('scroll', function() {
if ( $("#newsletter").hasClass('opened') ) {
var newScroll = $(document).scrollTop();
if (userScroll - newScroll > 100 || newScroll - userScroll > 100) {
$("#newsletter").removeClass('opened');
}
}
});
});
Actually, the Scroll function will take effect on every pixel the page is scrolled, which is too heavy in terms of performance.
As a result, if you just take the difference between newScroll & userScroll, the result may be wrong sometimes (because the new and old scroll positions will be updated shortly as the page is moving along)
Therefore, we can just set a time interval which checks the scroll position every 250 milliseconds (this will both increase performance and give time for users to scroll more than 20px as your requirement):
var didScroll;
var lastScrollTop = 0;
var delta = 20;
$(window).scroll(function(event){
didScroll = true;
});
setInterval(function() {
if (didScroll) {
hasScrolled();
didScroll = false;
}
}, 250);
function hasScrolled() {
var st = $(this).scrollTop();
// Return if they scroll less than 20px (delta)
if(Math.abs(lastScrollTop - st) <= delta)
return;
// Do what you want here
console.log("lastScrollTop: ",lastScrollTop, " - newScroll: ", st);
$('.navbar-collapse').collapse('hide');
$("#wrapper").removeClass('newsletter-opened');
$("#newsletter").removeClass('opened');
lastScrollTop = st;
}
EDITED VERSION BELOW:
(according to your fiddle, I deleted "use strict" and commented out the $('.navbar-collapse') & $('#wrapper'))
Would you mind trying this again (seems that some previous errors just prevented my code from executing)
$(document).ready(function(){
$("a.open-newsletter").on( "click", function() {
$("#newsletter").toggleClass('opened');
return false;
});
var didScroll;
var lastScrollTop = 0;
var delta = 20;
$(window).scroll(function(event){
didScroll = true;
});
setInterval(function() {
if (didScroll) {
hasScrolled();
didScroll = false;
}
}, 250);
function hasScrolled() {
var st = $(this).scrollTop();
// Return if they scroll less than 20px (delta)
if(Math.abs(lastScrollTop - st) <= delta)
return;
// Do what you want here
console.log("lastScrollTop: ",lastScrollTop, " - newScroll: ", st);
//$('.navbar-collapse').collapse('hide');
//$("#wrapper").removeClass('newsletter-opened');
$("#newsletter").removeClass('opened');
lastScrollTop = st;
}
});

How to control the speed of js nav scrolling

Hey Guys I found this really useful java script sticky side nav, and it works great! I don't much about js, i was just wondering if there was away to slow down the scrolling?
function redrawDotNav(){
var topNavHeight = 50;
var numDivs = $('section').length;
$('#dotNav li a').removeClass('active').parent('li').removeClass('active');
$('section').each(function(i,item){
var ele = $(item), nextTop;
console.log(ele.next().html());
if (typeof ele.next().offset() != "undefined") {
nextTop = ele.next().offset().top;
}
else {
nextTop = $(document).height();
}
if (ele.offset() !== null) {
thisTop = ele.offset().top - ((nextTop - ele.offset().top) / numDivs);
}
else {
thisTop = 0;
}
var docTop = $(document).scrollTop()+topNavHeight;
if(docTop >= thisTop && (docTop < nextTop)){
$('#dotNav li').eq(i).addClass('active');
}
});
}
$('#dotNav li').click(function(){
var id = $(this).find('a').attr("href"),
posi,
ele,
padding = $('.navbar-fixed-top').height();
ele = $(id);
posi = ($(ele).offset()||0).top - padding;
$('html, body').animate({scrollTop:posi}, 'slow');
return false;
});
demo
The line in your JavaScript code doing that is this:
$('html, body').animate({scrollTop:posi}, 'slow');
You can change the 'slow', to 'fast', and see the difference.
Learn more about the animate function here.
You can precisely control the speed on animate with duration. Here is the function signature:
animate(params, [duration], [easing], [callback])
The strings fast and slow can be supplied to indicate durations of 200ms and 600ms, respectively. The default speed is 400ms. You can adjust your speed by replacing nnn with the exact speed in milliseconds you want.
$('html, body').animate({scrollTop:posi}, nnn);

Make repeated scrollBy smoother like jQuery's animate scrollTop

How can I make a repeated scrollBy call smoother like when animating with jQuery's animate scrollTop?
Currently it is jumpy, the page jumps to and from the different scroll positions. How can I make it smoother?
Here is the scrollBy code:
window.scrollBy(0, -10*(scrollCount ? scrollCount<0 ? -1 : 1 : 0)) , 600*x); })(i);
And here is the for loop that contains it:
for(var i = 0; i < Math.abs(scrollCount); i++){
(function(x){
setTimeout(
window.scrollBy(0, -10*(scrollCount ? scrollCount<0 ? -1 : 1 : 0))
, 600*x); })(i);
}
}
Usage
First add this to your page.
scrollByAnimated = function(scrollY, duration){
var startTime = new Date().getTime();
var startY = window.scrollY;
var endY = startY + scrollY;
var currentY = startY;
var directionY = scrollY > 0 ? 'down' : 'up';
var animationComplete;
var count = 0;
var animationId;
if(duration === undefined){
duration = 250;//ms
}
//grab scroll events from the browser
var mousewheelevt=(/Firefox/i.test(navigator.userAgent))? "DOMMouseScroll" : "mousewheel" //FF doesn't recognize mousewheel as of FF3.x
//stop the current animation if its still going on an input from the user
var cancelAnimation = function () {
if(animationId!==undefined){
window.cancelAnimationFrame(animationId)
animationId=undefined;
}
}
if (document.attachEvent) {
//if IE (and Opera depending on user setting)
document.attachEvent("on"+mousewheelevt, cancelAnimation)
} else if (document.addEventListener) {
//WC3 browsers
document.addEventListener(mousewheelevt, cancelAnimation, false)
}
var step = function (a,b,c) {
var now = new Date().getTime();
var completeness = (now - startTime) / duration;
window.scrollTo(0, Math.round(startY + completeness * scrollY));
currentY = window.scrollY;
if(directionY === 'up') {
if (currentY === 0){
animationComplete = true;
}else{
animationComplete = currentY<=endY;
}
}
if(directionY === 'down') {
/*limitY is cross browser, we want the largest of these values*/
var limitY = Math.max( document.body.scrollHeight, document.body.offsetHeight, document.documentElement.clientHeight, document.documentElement.scrollHeight, document.documentElement.offsetHeight );
if(currentY + window.innerHeight === limitY){
animationComplete = true;
}else{
animationComplete = currentY>=endY;
}
}
if(animationComplete===true){
/*Stop animation*/
return;
}else{
/*repeat animation*/
if(count > 500){
return;
}else{
count++;
animationId = window.requestAnimationFrame(step);
}
}
};
/*start animation*/
step();
};
Then use it;
scrollByAnimated(100, 250);// change in scroll Y, duration in ms
Explanation
Here's a more robust version than your original code suggested you needed. Additional features include stop scrolling at the top and bottom of the page, uses requestAnimationFrame().
It also only supports scrolling up and down because thats all I need at this time. You'd be a cool, cool person if you added left and right to it.
It has only been tested in Chrome, so your milage may vary.
This code leverages requestAnimationFrame(). First scrollByAnimated() sets variables, then runs step() which loops until the duration has been reached.
At each frame it calculates the animation's completeness as a number from 0 to 1. This is the difference between the startTime and now, divided by duration.
This completeness value is then multiplied by the requested scrollY. This gives us our amount to scroll for each frame. Then we add the startY position to achieve a value that we can use window.scrollTo() to set the frame's position, rather than increment the current position.
try to use animate like this
$('html,body').animate({scrollTop: currentoffset},400);

html element doesn't move correctly with jQuery

I have to repair bottom slider on http://rhemapress.pl/www_wopr/ . If you see when you click right arrow twice, then animation back to start and animate again. Here when i click one on right arrow time this should be blocked and not possible to click second time.
Numer of moves right is created dynamicly by checkWidth();
function checkWidth() {
var elements = $('.items').children().length;
var width = Math.ceil(elements / 5) * 820;
return width;
}
This return realWidth witch is something like limit of offset. Variable offset is setted to 0 at start. So, if i click right, then in method moveRight() is checked if element can be moved and it's move. At end offset is increment by 820px (one page of slider), so if we've got 2 pages, then next move can't be called. But it is and this is problem! :/
My code
<script type="text/javascript">
$(document).ready(function() {
$('a.prev').bind('click',moveLeft);
$('a.next').bind('click',moveRight);
var realWidth = checkWidth();
realWidth -= 820;
var offset = 0;
function moveLeft(e) {
var position = $('.items').position();
var elements = $('.items').children().length;
if ((elements > 5) && ((offset - 820) >= 0) ) {
$('.items').animate({
'left': (position.left + 820)
}, 300, function() {
offset -= 820;
});
}
}
function moveRight(e) {
var position = $('.items').position();
var elements = $('.items').children().length;
if ((elements > 5) && ((offset + 820) <= realWidth)) {
$('.items').animate({
'left': (position.left - 820)
}, 300, function() {
offset += 820;
});
}
}
function checkWidth() {
var elements = $('.items').children().length;
var width = Math.ceil(elements / 5) * 820;
return width;
}
});
</script>
How can i do this correctly?
It seems like you want to prevent the click event from firing before the current animation is complete. You can do this by preventing the rest of the function from executing if the element is currently being animated:
function moveLeft(e) {
if ($(this).is(":animated")) {
return false;
}

Smooth scroll without the use of jQuery

I'm coding up a page where I only want to use raw JavaScript code for UI without any interference of plugins or frameworks.
And now I'm struggling with finding a way to scroll over the page smoothly without jQuery.
Native browser smooth scrolling in JavaScript is like this:
// scroll to specific values,
// same as window.scroll() method.
// for scrolling a particular distance, use window.scrollBy().
window.scroll({
top: 2500,
left: 0,
behavior: 'smooth'
});
// scroll certain amounts from current position
window.scrollBy({
top: 100, // negative value acceptable
left: 0,
behavior: 'smooth'
});
// scroll to a certain element
document.querySelector('.hello').scrollIntoView({
behavior: 'smooth'
});
Try this smooth scrolling demo, or an algorithm like:
Get the current top location using self.pageYOffset
Get the position of element till where you want to scroll to: element.offsetTop
Do a for loop to reach there, which will be quite fast or use a timer to do smooth scroll till that position using window.scrollTo
See also the other popular answer to this question.
Andrew Johnson's original code:
function currentYPosition() {
// Firefox, Chrome, Opera, Safari
if (self.pageYOffset) return self.pageYOffset;
// Internet Explorer 6 - standards mode
if (document.documentElement && document.documentElement.scrollTop)
return document.documentElement.scrollTop;
// Internet Explorer 6, 7 and 8
if (document.body.scrollTop) return document.body.scrollTop;
return 0;
}
function elmYPosition(eID) {
var elm = document.getElementById(eID);
var y = elm.offsetTop;
var node = elm;
while (node.offsetParent && node.offsetParent != document.body) {
node = node.offsetParent;
y += node.offsetTop;
} return y;
}
function smoothScroll(eID) {
var startY = currentYPosition();
var stopY = elmYPosition(eID);
var distance = stopY > startY ? stopY - startY : startY - stopY;
if (distance < 100) {
scrollTo(0, stopY); return;
}
var speed = Math.round(distance / 100);
if (speed >= 20) speed = 20;
var step = Math.round(distance / 25);
var leapY = stopY > startY ? startY + step : startY - step;
var timer = 0;
if (stopY > startY) {
for ( var i=startY; i<stopY; i+=step ) {
setTimeout("window.scrollTo(0, "+leapY+")", timer * speed);
leapY += step; if (leapY > stopY) leapY = stopY; timer++;
} return;
}
for ( var i=startY; i>stopY; i-=step ) {
setTimeout("window.scrollTo(0, "+leapY+")", timer * speed);
leapY -= step; if (leapY < stopY) leapY = stopY; timer++;
}
}
Related links:
https://www.sitepoint.com/smooth-scrolling-vanilla-javascript/
https://github.com/zengabor/zenscroll/blob/dist/zenscroll.js
https://github.com/cferdinandi/smooth-scroll/blob/master/src/js/smooth-scroll.js
https://github.com/alicelieutier/smoothScroll/blob/master/smoothscroll.js
Algorithm
Scrolling an element requires changing its scrollTop value over time. For a given point in time, calculate a new scrollTop value. To animate smoothly, interpolate using a smooth-step algorithm.
Calculate scrollTop as follows:
var point = smooth_step(start_time, end_time, now);
var scrollTop = Math.round(start_top + (distance * point));
Where:
start_time is the time the animation started;
end_time is when the animation will end (start_time + duration);
start_top is the scrollTop value at the beginning; and
distance is the difference between the desired end value and the start value (target - start_top).
A robust solution should detect when animating is interrupted, and more. Read my post about Smooth Scrolling without jQuery for details.
Demo
See the JSFiddle.
Implementation
The code:
/**
Smoothly scroll element to the given target (element.scrollTop)
for the given duration
Returns a promise that's fulfilled when done, or rejected if
interrupted
*/
var smooth_scroll_to = function(element, target, duration) {
target = Math.round(target);
duration = Math.round(duration);
if (duration < 0) {
return Promise.reject("bad duration");
}
if (duration === 0) {
element.scrollTop = target;
return Promise.resolve();
}
var start_time = Date.now();
var end_time = start_time + duration;
var start_top = element.scrollTop;
var distance = target - start_top;
// based on http://en.wikipedia.org/wiki/Smoothstep
var smooth_step = function(start, end, point) {
if(point <= start) { return 0; }
if(point >= end) { return 1; }
var x = (point - start) / (end - start); // interpolation
return x*x*(3 - 2*x);
}
return new Promise(function(resolve, reject) {
// This is to keep track of where the element's scrollTop is
// supposed to be, based on what we're doing
var previous_top = element.scrollTop;
// This is like a think function from a game loop
var scroll_frame = function() {
if(element.scrollTop != previous_top) {
reject("interrupted");
return;
}
// set the scrollTop for this frame
var now = Date.now();
var point = smooth_step(start_time, end_time, now);
var frameTop = Math.round(start_top + (distance * point));
element.scrollTop = frameTop;
// check if we're done!
if(now >= end_time) {
resolve();
return;
}
// If we were supposed to scroll but didn't, then we
// probably hit the limit, so consider it done; not
// interrupted.
if(element.scrollTop === previous_top
&& element.scrollTop !== frameTop) {
resolve();
return;
}
previous_top = element.scrollTop;
// schedule next frame for execution
setTimeout(scroll_frame, 0);
}
// boostrap the animation process
setTimeout(scroll_frame, 0);
});
}
You can use the new Scroll Behaviour CSS Property.
for example, add the below line to your CSS.
html{
scroll-behavior:smooth;
}
and this will result in a native smooth scrolling feature.
see demo here
All modern browsers support the scroll-behavior property.
Read More about Scroll behavior
I've made an example without jQuery here : http://codepen.io/sorinnn/pen/ovzdq
/**
by Nemes Ioan Sorin - not an jQuery big fan
therefore this script is for those who love the old clean coding style
#id = the id of the element who need to bring into view
Note : this demo scrolls about 12.700 pixels from Link1 to Link3
*/
(function()
{
window.setTimeout = window.setTimeout; //
})();
var smoothScr = {
iterr : 30, // set timeout miliseconds ..decreased with 1ms for each iteration
tm : null, //timeout local variable
stopShow: function()
{
clearTimeout(this.tm); // stopp the timeout
this.iterr = 30; // reset milisec iterator to original value
},
getRealTop : function (el) // helper function instead of jQuery
{
var elm = el;
var realTop = 0;
do
{
realTop += elm.offsetTop;
elm = elm.offsetParent;
}
while(elm);
return realTop;
},
getPageScroll : function() // helper function instead of jQuery
{
var pgYoff = window.pageYOffset || document.body.scrollTop || document.documentElement.scrollTop;
return pgYoff;
},
anim : function (id) // the main func
{
this.stopShow(); // for click on another button or link
var eOff, pOff, tOff, scrVal, pos, dir, step;
eOff = document.getElementById(id).offsetTop; // element offsetTop
tOff = this.getRealTop(document.getElementById(id).parentNode); // terminus point
pOff = this.getPageScroll(); // page offsetTop
if (pOff === null || isNaN(pOff) || pOff === 'undefined') pOff = 0;
scrVal = eOff - pOff; // actual scroll value;
if (scrVal > tOff)
{
pos = (eOff - tOff - pOff);
dir = 1;
}
if (scrVal < tOff)
{
pos = (pOff + tOff) - eOff;
dir = -1;
}
if(scrVal !== tOff)
{
step = ~~((pos / 4) +1) * dir;
if(this.iterr > 1) this.iterr -= 1;
else this.itter = 0; // decrease the timeout timer value but not below 0
window.scrollBy(0, step);
this.tm = window.setTimeout(function()
{
smoothScr.anim(id);
}, this.iterr);
}
if(scrVal === tOff)
{
this.stopShow(); // reset function values
return;
}
}
}
Modern browsers has support for CSS "scroll-behavior: smooth" property. So, we even don't need any Javascript at all for this. Just add this for the "html" element, and use usual anchors and links.
scroll-behavior MDN docs
I recently set out to solve this problem in a situation where jQuery wasn't an option, so I'm logging my solution here just for posterity.
var scroll = (function() {
var elementPosition = function(a) {
return function() {
return a.getBoundingClientRect().top;
};
};
var scrolling = function( elementID ) {
var el = document.getElementById( elementID ),
elPos = elementPosition( el ),
duration = 400,
increment = Math.round( Math.abs( elPos() )/40 ),
time = Math.round( duration/increment ),
prev = 0,
E;
function scroller() {
E = elPos();
if (E === prev) {
return;
} else {
prev = E;
}
increment = (E > -20 && E < 20) ? ((E > - 5 && E < 5) ? 1 : 5) : increment;
if (E > 1 || E < -1) {
if (E < 0) {
window.scrollBy( 0,-increment );
} else {
window.scrollBy( 0,increment );
}
setTimeout(scroller, time);
} else {
el.scrollTo( 0,0 );
}
}
scroller();
};
return {
To: scrolling
}
})();
/* usage */
scroll.To('elementID');
The scroll() function uses the Revealing Module Pattern to pass the target element's id to its scrolling() function, via scroll.To('id'), which sets the values used by the scroller() function.
Breakdown
In scrolling():
el : the target DOM object
elPos : returns a function via elememtPosition() which gives the position of the target element relative to the top of the page each time it's called.
duration : transition time in milliseconds.
increment : divides the starting position of the target element into 40 steps.
time : sets the timing of each step.
prev : the target element's previous position in scroller().
E : holds the target element's position in scroller().
The actual work is done by the scroller() function which continues to call itself (via setTimeout()) until the target element is at the top of the page or the page can scroll no more.
Each time scroller() is called it checks the current position of the target element (held in variable E) and if that is > 1 OR < -1 and if the page is still scrollable shifts the window by increment pixels - up or down depending if E is a positive or negative value. When E is neither > 1 OR < -1, or E === prev the function stops. I added the DOMElement.scrollTo() method on completion just to make sure the target element was bang on the top of the window (not that you'd notice it being out by a fraction of a pixel!).
The if statement on line 2 of scroller() checks to see if the page is scrolling (in cases where the target might be towards the bottom of the page and the page can scroll no further) by checking E against its previous position (prev).
The ternary condition below it reduce the increment value as E approaches zero. This stops the page overshooting one way and then bouncing back to overshoot the other, and then bouncing back to overshoot the other again, ping-pong style, to infinity and beyond.
If your page is more that c.4000px high you might want to increase the values in the ternary expression's first condition (here at +/-20) and/or the divisor which sets the increment value (here at 40).
Playing about with duration, the divisor which sets increment, and the values in the ternary condition of scroller() should allow you to tailor the function to suit your page.
JSFiddle
N.B.Tested in up-to-date versions of Firefox and Chrome on Lubuntu, and Firefox, Chrome and IE on Windows8.
I've made something like this.
I have no idea if its working in IE8.
Tested in IE9, Mozilla, Chrome, Edge.
function scroll(toElement, speed) {
var windowObject = window;
var windowPos = windowObject.pageYOffset;
var pointer = toElement.getAttribute('href').slice(1);
var elem = document.getElementById(pointer);
var elemOffset = elem.offsetTop;
var counter = setInterval(function() {
windowPos;
if (windowPos > elemOffset) { // from bottom to top
windowObject.scrollTo(0, windowPos);
windowPos -= speed;
if (windowPos <= elemOffset) { // scrolling until elemOffset is higher than scrollbar position, cancel interval and set scrollbar to element position
clearInterval(counter);
windowObject.scrollTo(0, elemOffset);
}
} else { // from top to bottom
windowObject.scrollTo(0, windowPos);
windowPos += speed;
if (windowPos >= elemOffset) { // scroll until scrollbar is lower than element, cancel interval and set scrollbar to element position
clearInterval(counter);
windowObject.scrollTo(0, elemOffset);
}
}
}, 1);
}
//call example
var navPointer = document.getElementsByClassName('nav__anchor');
for (i = 0; i < navPointer.length; i++) {
navPointer[i].addEventListener('click', function(e) {
scroll(this, 18);
e.preventDefault();
});
}
Description
pointer—get element and chceck if it has attribute "href" if yes,
get rid of "#"
elem—pointer variable without "#"
elemOffset—offset of "scroll to" element from the top of the page
You can use
document.querySelector('your-element').scrollIntoView({behavior: 'smooth'});
If you want to scroll top the top of the page, you can just place an empty element in the top, and smooth scroll to that one.
With using the following smooth scrolling is working fine:
html {
scroll-behavior: smooth;
}
<script>
var set = 0;
function animatescroll(x, y) {
if (set == 0) {
var val72 = 0;
var val73 = 0;
var setin = 0;
set = 1;
var interval = setInterval(function() {
if (setin == 0) {
val72++;
val73 += x / 1000;
if (val72 == 1000) {
val73 = 0;
interval = clearInterval(interval);
}
document.getElementById(y).scrollTop = val73;
}
}, 1);
}
}
</script>
x = scrollTop
y = id of the div that is used to scroll
Note:
For making the body to scroll give the body an ID.
Here is my solution. Works in most browsers
document.getElementById("scrollHere").scrollIntoView({behavior: "smooth"});
Docs
document.getElementById("end").scrollIntoView({behavior: "smooth"});
body {margin: 0px; display: block; height: 100%; background-image: linear-gradient(red, yellow);}
.start {display: block; margin: 100px 10px 1000px 0px;}
.end {display: block; margin: 0px 0px 100px 0px;}
<div class="start">Start</div>
<div class="end" id="end">End</div>
There are many different methods for smooth scrolling in JavaScript. The most common ones are listed below.
To scroll to a certain position in an exact amount of time, window.requestAnimationFrame can be put to use, calculating the appropriate current position each time. setTimeout can be used to a similar effect when requestAnimationFrame is not supported. (To scroll to a specific element with the function below, just set the position to element.offsetTop.)
/*
#param pos: the y-position to scroll to (in pixels)
#param time: the exact amount of time the scrolling will take (in milliseconds)
*/
function scrollToSmoothly(pos, time) {
var currentPos = window.pageYOffset;
var start = null;
if(time == null) time = 500;
pos = +pos, time = +time;
window.requestAnimationFrame(function step(currentTime) {
start = !start ? currentTime : start;
var progress = currentTime - start;
if (currentPos < pos) {
window.scrollTo(0, ((pos - currentPos) * progress / time) + currentPos);
} else {
window.scrollTo(0, currentPos - ((currentPos - pos) * progress / time));
}
if (progress < time) {
window.requestAnimationFrame(step);
} else {
window.scrollTo(0, pos);
}
});
}
Demo:
/*
#param time: the exact amount of time the scrolling will take (in milliseconds)
#param pos: the y-position to scroll to (in pixels)
*/
function scrollToSmoothly(pos, time) {
var currentPos = window.pageYOffset;
var start = null;
if(time == null) time = 500;
pos = +pos, time = +time;
window.requestAnimationFrame(function step(currentTime) {
start = !start ? currentTime : start;
var progress = currentTime - start;
if (currentPos < pos) {
window.scrollTo(0, ((pos - currentPos) * progress / time) + currentPos);
} else {
window.scrollTo(0, currentPos - ((currentPos - pos) * progress / time));
}
if (progress < time) {
window.requestAnimationFrame(step);
} else {
window.scrollTo(0, pos);
}
});
}
<button onClick="scrollToSmoothly(document.querySelector('div').offsetTop, 300)">
Scroll To Div (300ms)
</button>
<button onClick="scrollToSmoothly(document.querySelector('div').offsetTop, 200)">
Scroll To Div (200ms)
</button>
<button onClick="scrollToSmoothly(document.querySelector('div').offsetTop, 100)">
Scroll To Div (100ms)
</button>
<button onClick="scrollToSmoothly(document.querySelector('div').offsetTop, 50)">
Scroll To Div (50ms)
</button>
<button onClick="scrollToSmoothly(document.querySelector('div').offsetTop, 1000)">
Scroll To Div (1000ms)
</button>
<div style="margin: 500px 0px;">
DIV<p/>
<button onClick="scrollToSmoothly(0, 500)">
Back To Top
</button>
<button onClick="scrollToSmoothly(document.body.scrollHeight)">
Scroll To Bottom
</button>
</div>
<div style="margin: 500px 0px;">
</div>
<button style="margin-top: 100px;" onClick="scrollToSmoothly(500, 3000)">
Scroll To y-position 500px (3000ms)
</button>
For more complex cases, the SmoothScroll.js library can be used, which handles smooth scrolling both vertically and horizontally, scrolling inside other container elements, different easing behaviors, scrolling relatively from the current position, and more.
var easings = document.getElementById("easings");
for(var key in smoothScroll.easing){
if(smoothScroll.easing.hasOwnProperty(key)){
var option = document.createElement('option');
option.text = option.value = key;
easings.add(option);
}
}
document.getElementById('to-bottom').addEventListener('click', function(e){
smoothScroll({yPos: 'end', easing: easings.value, duration: 2000});
});
document.getElementById('to-top').addEventListener('click', function(e){
smoothScroll({yPos: 'start', easing: easings.value, duration: 2000});
});
<script src="https://cdn.jsdelivr.net/gh/LieutenantPeacock/SmoothScroll#1.2.0/src/smoothscroll.min.js" integrity="sha384-UdJHYJK9eDBy7vML0TvJGlCpvrJhCuOPGTc7tHbA+jHEgCgjWpPbmMvmd/2bzdXU" crossorigin="anonymous"></script>
<!-- Taken from one of the library examples -->
Easing: <select id="easings"></select>
<button id="to-bottom">Scroll To Bottom</button>
<br>
<button id="to-top" style="margin-top: 5000px;">Scroll To Top</button>
Alternatively, you can pass an options object to window.scroll which scrolls to a specific x and y position and window.scrollBy which scrolls a certain amount from the current position:
// Scroll to specific values
// scrollTo is the same
window.scroll({
top: 2500,
left: 0,
behavior: 'smooth'
});
// Scroll certain amounts from current position
window.scrollBy({
top: 100, // could be negative value
left: 0,
behavior: 'smooth'
});
Demo:
<button onClick="scrollToDiv()">Scroll To Element</button>
<div style="margin: 500px 0px;">Div</div>
<script>
function scrollToDiv(){
var elem = document.querySelector("div");
window.scroll({
top: elem.offsetTop,
left: 0,
behavior: 'smooth'
});
}
</script>
If you only need to scroll to an element, not a specific position in the document, you can use Element.scrollIntoView with behavior set to smooth.
document.getElementById("elemID").scrollIntoView({
behavior: 'smooth'
});
Demo:
<button onClick="scrollToDiv()">Scroll To Element</button>
<div id="myDiv" style="margin: 500px 0px;">Div</div>
<script>
function scrollToDiv(){
document.getElementById("myDiv").scrollIntoView({
behavior: 'smooth'
});
}
</script>
Modern browsers support the scroll-behavior CSS property, which can be used to make scrolling in the document smooth (without the need for JavaScript). Anchor tags can be used for this by giving the anchor tag a href of # plus the id of the element to scroll to). You can also set the scroll-behavior property for a specific container like a div to make its contents scroll smoothly.
Demo:
html, body{
scroll-behavior: smooth;
}
Scroll To Element
<div id="elem" style="margin: 500px 0px;">Div</div>
Here's my variation:
let MenuItem = function ( _menuItem ) {
// I had a sticky header, so its height had to be taken into account when scrolling
let _header = document.querySelector('.site-header');
let _scrollToBlock = function( e, menuItem ) {
let id = menuItem.getAttribute('href'), // the href attribute stores the id of the block to which the scroll will be
headerHeight = _header.offsetHeight; // determine the height of the header
id = id.replace(/#/, ''); // remove the # sign from the id block
let elem = document.getElementById( id ), // define the element to which we will scroll
top = elem.getBoundingClientRect().top + window.scrollY - headerHeight; // determine the height of the scroll
window.scroll({
top: top,
left: 0,
behavior: 'smooth'
});
},
_addEvents = function() {
_menuItem.addEventListener('click', function (e){
e.preventDefault(); // Disable redirect on click
_scrollToBlock(e, _menuItem);
});
},
_init = function() {
_addEvents();
};
_init();
};
// Initialize the class MenuItem to all links with class .menu__item
document.querySelectorAll('.menu__item').forEach( function(item) {
new MenuItem(item);
} );
Here's the code that worked for me.
`$('a[href*="#"]')
.not('[href="#"]')
.not('[href="#0"]')
.click(function(event) {
if (
location.pathname.replace(/^\//, '') == this.pathname.replace(/^\//, '')
&&
location.hostname == this.hostname
) {
var target = $(this.hash);
target = target.length ? target : $('[name=' + this.hash.slice(1) + ']');
if (target.length) {
event.preventDefault();
$('html, body').animate({
scrollTop: target.offset().top
}, 1000, function() {
var $target = $(target);
$target.focus();
if ($target.is(":focus")) {
return false;
} else {
$target.attr('tabindex','-1');
$target.focus();
};
});
}
}
});
`

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