Smooth scroll when scrolling - javascript

I have this JavaScript code (PasteBin, Fiddle) which scrolls smoothly. It works just perfect but it needs one more thing:
var EPPZScrollTo =
{
/**
* Helpers.
*/
documentVerticalScrollPosition: function()
{
if (self.pageYOffset) return self.pageYOffset; // Firefox, Chrome, Opera, Safari.
if (document.documentElement && document.documentElement.scrollTop) return document.documentElement.scrollTop; // Internet Explorer 6 (standards mode).
if (document.body.scrollTop) return document.body.scrollTop; // Internet Explorer 6, 7 and 8.
return 0; // None of the above.
},
viewportHeight: function()
{ return (document.compatMode === "CSS1Compat") ? document.documentElement.clientHeight : document.body.clientHeight; },
documentHeight: function()
{ return (document.height !== undefined) ? document.height : document.body.offsetHeight; },
documentMaximumScrollPosition: function()
{ return this.documentHeight() - this.viewportHeight(); },
elementVerticalClientPositionById: function(id)
{
var element = document.getElementById(id);
var rectangle = element.getBoundingClientRect();
return rectangle.top;
},
/**
* Animation tick.
*/
scrollVerticalTickToPosition: function(currentPosition, targetPosition)
{
var filter = 0.1;
var fps = 60;
var difference = parseFloat(targetPosition) - parseFloat(currentPosition);
// Snap, then stop if arrived.
var arrived = (Math.abs(difference) <= 0.5);
if (arrived)
{
// Apply target.
scrollTo(0.0, targetPosition);
return;
}
// Filtered position.
currentPosition = (parseFloat(currentPosition) * (1.0 - filter)) + (parseFloat(targetPosition) * filter);
// Apply target.
scrollTo(0.0, Math.round(currentPosition));
// Schedule next tick.
setTimeout("EPPZScrollTo.scrollVerticalTickToPosition("+currentPosition+", "+targetPosition+")", (2000 / fps));
},
/**
* For public use.
*
* #param id The id of the element to scroll to.
* #param padding Top padding to apply above element.
*/
scrollVerticalToElementById: function(id, padding)
{
var element = document.getElementById(id);
if (element == null)
{
console.warn('Cannot find element with id \''+id+'\'.');
return;
}
var targetPosition = this.documentVerticalScrollPosition() + this.elementVerticalClientPositionById(id) - padding;
var currentPosition = this.documentVerticalScrollPosition();
// Clamp.
var maximumScrollPosition = this.documentMaximumScrollPosition();
if (targetPosition > maximumScrollPosition) targetPosition = maximumScrollPosition;
// Start animation.
this.scrollVerticalTickToPosition(currentPosition, targetPosition);
}
};
I would like it to stop auto-scrolling upon scroll. As it is right now, it messes up when you scroll at the same time of it auto-scrolling.

Add additional variable that you use to keep track of has user started scrolling.
var user_is_scrolling = false;
Then schedule the next scroll only if the user hasn't started scrolling:
if(!user_is_scrolling){
setTimeout("EPPZScrollTo.scrollVerticalTickToPosition("+currentPosition+", "+targetPosition+")", (2000 / fps));
}
Then keep track of the window scroll events
var scroll_timeout;
window.onscroll = function(e) {
//clear the timeout if it happens to exist
clearTimeout(scroll_timeout);
//set scrolling to true
user_is_scrolling = true;
//set timeout for setting user_is_scrolling to false 250ms after
//user has actually stopped scrolling
scroll_timeout = setTimeout(function(){
user_is_scrolling = false;
}, 250);
}
Fiddle: http://jsfiddle.net/UT8H6/4/

Related

HTML Element Height Keeps Incrementing by the Second

Purchased an off the shelf theme for my portfolio site (yes, yes...I'm too busy to design my own right now lol). Anyway I seem to be having an issue, and I have no idea when it started, where my html height keeps growing by 30-60px every 1-2sec.
I've tried viewing the console, however I can't find anything that's triggering this. I'm assuming that some funking Javascript is at play, and need help possibly tracking it down.
Anyone wanna lend a hand here...?
My Site
UPDATE: It seems to be caused by the smoothscroll.js file. Can any JS pro help me find the offending line of code?
// SmoothScroll v1.2.1
// Licensed under the terms of the MIT license.
// People involved
// - Balazs Galambosi (maintainer)
// - Patrick Brunner (original idea)
// - Michael Herf (Pulse Algorithm)
// - Justin Force (Resurect)
// Scroll Variables (tweakable)
var framerate = 150; // [Hz]
var animtime = 800; // [px]
var stepsize = 80; // [px]
// Pulse (less tweakable)
// ratio of "tail" to "acceleration"
var pulseAlgorithm = true;
var pulseScale = 8;
var pulseNormalize = 1;
// Acceleration
var acceleration = true;
var accelDelta = 10; // 20
var accelMax = 1; // 1
// Keyboard Settings
var keyboardsupport = true; // option
var disableKeyboard = false; // other reasons
var arrowscroll = 50; // [px]
// Excluded pages
var exclude = "";
var disabled = false;
// Other Variables
var frame = false;
var direction = { x: 0, y: 0 };
var initdone = false;
var fixedback = true;
var root = document.documentElement;
var activeElement;
var key = { left: 37, up: 38, right: 39, down: 40, spacebar: 32, pageup: 33, pagedown: 34, end: 35, home: 36 };
/**
* Sets up scrolls array, determines if frames are involved.
*/
function init() {
if (!document.body) return;
var body = document.body;
var html = document.documentElement;
var windowHeight = window.innerHeight;
var scrollHeight = body.scrollHeight;
// check compat mode for root element
root = (document.compatMode.indexOf('CSS') >= 0) ? html : body;
activeElement = body;
initdone = true;
// Checks if this script is running in a frame
if (top != self) {
frame = true;
}
/**
* This fixes a bug where the areas left and right to
* the content does not trigger the onmousewheel event
* on some pages. e.g.: html, body { height: 100% }
*/
else if (scrollHeight > windowHeight &&
(body.offsetHeight <= windowHeight ||
html.offsetHeight <= windowHeight)) {
// DOMChange (throttle): fix height
var pending = false;
var refresh = function() {
if (!pending && html.scrollHeight != document.height) {
pending = true; // add a new pending action
setTimeout(function(){
html.style.height = document.height + 'px';
pending = false;
}, 500); // act rarely to stay fast
}
};
html.style.height = '';
setTimeout(refresh, 10);
addEvent("DOMNodeInserted", refresh);
addEvent("DOMNodeRemoved", refresh);
// clearfix
if (root.offsetHeight <= windowHeight) {
var underlay = document.createElement("div");
underlay.style.clear = "both";
body.appendChild(underlay);
}
}
// gmail performance fix
if (document.URL.indexOf("mail.google.com") > -1) {
var s = document.createElement("style");
s.innerHTML = ".iu { visibility: hidden }";
(document.getElementsByTagName("head")[0] || html).appendChild(s);
}
// disable fixed background
if (!fixedback && !disabled) {
body.style.backgroundAttachment = "scroll";
html.style.backgroundAttachment = "scroll";
}
}
/************************************************
* SCROLLING
************************************************/
var que = [];
var pending = false;
var lastScroll = +new Date;
/**
* Pushes scroll actions to the scrolling queue.
*/
function scrollArray(elem, left, top, delay) {
delay || (delay = 1000);
directionCheck(left, top);
if (acceleration) {
var now = +new Date;
var elapsed = now - lastScroll;
if (elapsed < accelDelta) {
var factor = (1 + (30 / elapsed)) / 2;
if (factor > 1) {
factor = Math.min(factor, accelMax);
left *= factor;
top *= factor;
}
}
lastScroll = +new Date;
}
// push a scroll command
que.push({
x: left,
y: top,
lastX: (left < 0) ? 0.99 : -0.99,
lastY: (top < 0) ? 0.99 : -0.99,
start: +new Date
});
// don't act if there's a pending queue
if (pending) {
return;
}
var scrollWindow = (elem === document.body);
var step = function() {
var now = +new Date;
var scrollX = 0;
var scrollY = 0;
for (var i = 0; i < que.length; i++) {
var item = que[i];
var elapsed = now - item.start;
var finished = (elapsed >= animtime);
// scroll position: [0, 1]
var position = (finished) ? 1 : elapsed / animtime;
// easing [optional]
if (pulseAlgorithm) {
position = pulse(position);
}
// only need the difference
var x = (item.x * position - item.lastX) >> 0;
var y = (item.y * position - item.lastY) >> 0;
// add this to the total scrolling
scrollX += x;
scrollY += y;
// update last values
item.lastX += x;
item.lastY += y;
// delete and step back if it's over
if (finished) {
que.splice(i, 1); i--;
}
}
// scroll left and top
if (scrollWindow) {
window.scrollBy(scrollX, scrollY)
}
else {
if (scrollX) elem.scrollLeft += scrollX;
if (scrollY) elem.scrollTop += scrollY;
}
// clean up if there's nothing left to do
if (!left && !top) {
que = [];
}
if (que.length) {
requestFrame(step, elem, (delay / framerate + 1));
} else {
pending = false;
}
}
// start a new queue of actions
requestFrame(step, elem, 0);
pending = true;
}
/***********************************************
* EVENTS
***********************************************/
/**
* Mouse wheel handler.
* #param {Object} event
*/
function wheel(event) {
if (!initdone) {
init();
}
var target = event.target;
var overflowing = overflowingAncestor(target);
// use default if there's no overflowing
// element or default action is prevented
if (!overflowing || event.defaultPrevented ||
isNodeName(activeElement, "embed") ||
(isNodeName(target, "embed") && /\.pdf/i.test(target.src))) {
return true;
}
var deltaX = event.wheelDeltaX || 0;
var deltaY = event.wheelDeltaY || 0;
// use wheelDelta if deltaX/Y is not available
if (!deltaX && !deltaY) {
deltaY = event.wheelDelta || 0;
}
// scale by step size
// delta is 120 most of the time
// synaptics seems to send 1 sometimes
if (Math.abs(deltaX) > 1.2) {
deltaX *= stepsize / 120;
}
if (Math.abs(deltaY) > 1.2) {
deltaY *= stepsize / 120;
}
scrollArray(overflowing, -deltaX, -deltaY);
event.preventDefault();
}
/**
* Keydown event handler.
* #param {Object} event
*/
function keydown(event) {
var target = event.target;
var modifier = event.ctrlKey || event.altKey || event.metaKey ||
(event.shiftKey && event.keyCode !== key.spacebar);
// do nothing if user is editing text
// or using a modifier key (except shift)
// or in a dropdown
if ( /input|textarea|select|embed/i.test(target.nodeName) ||
target.isContentEditable ||
event.defaultPrevented ||
modifier ) {
return true;
}
// spacebar should trigger button press
if (isNodeName(target, "button") &&
event.keyCode === key.spacebar) {
return true;
}
var shift, x = 0, y = 0;
var elem = overflowingAncestor(activeElement);
var clientHeight = elem.clientHeight;
if (elem == document.body) {
clientHeight = window.innerHeight;
}
switch (event.keyCode) {
case key.up:
y = -arrowscroll;
break;
case key.down:
y = arrowscroll;
break;
case key.spacebar: // (+ shift)
shift = event.shiftKey ? 1 : -1;
y = -shift * clientHeight * 0.9;
break;
case key.pageup:
y = -clientHeight * 0.9;
break;
case key.pagedown:
y = clientHeight * 0.9;
break;
case key.home:
y = -elem.scrollTop;
break;
case key.end:
var damt = elem.scrollHeight - elem.scrollTop - clientHeight;
y = (damt > 0) ? damt+10 : 0;
break;
case key.left:
x = -arrowscroll;
break;
case key.right:
x = arrowscroll;
break;
default:
return true; // a key we don't care about
}
scrollArray(elem, x, y);
event.preventDefault();
}
/**
* Mousedown event only for updating activeElement
*/
function mousedown(event) {
activeElement = event.target;
}
/***********************************************
* OVERFLOW
***********************************************/
var cache = {}; // cleared out every once in while
setInterval(function(){ cache = {}; }, 10 * 1000);
var uniqueID = (function() {
var i = 0;
return function (el) {
return el.uniqueID || (el.uniqueID = i++);
};
})();
function setCache(elems, overflowing) {
for (var i = elems.length; i--;)
cache[uniqueID(elems[i])] = overflowing;
return overflowing;
}
function overflowingAncestor(el) {
var elems = [];
var rootScrollHeight = root.scrollHeight;
do {
var cached = cache[uniqueID(el)];
if (cached) {
return setCache(elems, cached);
}
elems.push(el);
if (rootScrollHeight === el.scrollHeight) {
if (!frame || root.clientHeight + 10 < rootScrollHeight) {
return setCache(elems, document.body); // scrolling root in WebKit
}
} else if (el.clientHeight + 10 < el.scrollHeight) {
overflow = getComputedStyle(el, "").getPropertyValue("overflow-y");
if (overflow === "scroll" || overflow === "auto") {
return setCache(elems, el);
}
}
} while (el = el.parentNode);
}
/***********************************************
* HELPERS
***********************************************/
function addEvent(type, fn, bubble) {
window.addEventListener(type, fn, (bubble||false));
}
function removeEvent(type, fn, bubble) {
window.removeEventListener(type, fn, (bubble||false));
}
function isNodeName(el, tag) {
return (el.nodeName||"").toLowerCase() === tag.toLowerCase();
}
function directionCheck(x, y) {
x = (x > 0) ? 1 : -1;
y = (y > 0) ? 1 : -1;
if (direction.x !== x || direction.y !== y) {
direction.x = x;
direction.y = y;
que = [];
lastScroll = 0;
}
}
var requestFrame = (function(){
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
function(callback, element, delay){
window.setTimeout(callback, delay || (1000/60));
};
})();
/***********************************************
* PULSE
***********************************************/
/**
* Viscous fluid with a pulse for part and decay for the rest.
* - Applies a fixed force over an interval (a damped acceleration), and
* - Lets the exponential bleed away the velocity over a longer interval
* - Michael Herf, http://stereopsis.com/stopping/
*/
function pulse_(x) {
var val, start, expx;
// test
x = x * pulseScale;
if (x < 1) { // acceleartion
val = x - (1 - Math.exp(-x));
} else { // tail
// the previous animation ended here:
start = Math.exp(-1);
// simple viscous drag
x -= 1;
expx = 1 - Math.exp(-x);
val = start + (expx * (1 - start));
}
return val * pulseNormalize;
}
function pulse(x) {
if (x >= 1) return 1;
if (x <= 0) return 0;
if (pulseNormalize == 1) {
pulseNormalize /= pulse_(1);
}
return pulse_(x);
}
addEvent("mousedown", mousedown);
addEvent("mousewheel", wheel);
addEvent("load", init);
Not sure what's going on here, but the issue with smoothscroll.js still stands. Disabling it seems to have no effect on the rest of my site though so I'm moving forward.

Scroll smoothly to specific element on page

I want to have 4 buttons/links on the beginning of the page, and under them the content.
On the buttons I put this code:
Scroll to element 1
Scroll to element 2
Scroll to element 3
Scroll to element 4
And under links there will be content:
<h2 id="idElement1">Element1</h2>
content....
<h2 id="idElement2">Element2</h2>
content....
<h2 id="idElement3">Element3</h2>
content....
<h2 id="idElement4">Element4</h2>
content....
It is working now, but cannot make it look more smooth.
I used this code, but cannot get it to work.
$('html, body').animate({
scrollTop: $("#elementID").offset().top
}, 2000);
Any suggestions? Thank you.
Edit: and the fiddle: http://jsfiddle.net/WxJLx/2/
Super smoothly with requestAnimationFrame
For smoothly rendered scrolling animation one could use window.requestAnimationFrame() which performs better with rendering than regular setTimeout() solutions.
A basic example looks like this. Function step is called for browser's every animation frame and allows for better time management of repaints, and thus increasing performance.
function doScrolling(elementY, duration) {
var startingY = window.pageYOffset;
var diff = elementY - startingY;
var start;
// Bootstrap our animation - it will get called right before next frame shall be rendered.
window.requestAnimationFrame(function step(timestamp) {
if (!start) start = timestamp;
// Elapsed milliseconds since start of scrolling.
var time = timestamp - start;
// Get percent of completion in range [0, 1].
var percent = Math.min(time / duration, 1);
window.scrollTo(0, startingY + diff * percent);
// Proceed with animation as long as we wanted it to.
if (time < duration) {
window.requestAnimationFrame(step);
}
})
}
For element's Y position use functions in other answers or the one in my below-mentioned fiddle.
I set up a bit more sophisticated function with easing support and proper scrolling to bottom-most elements:
https://jsfiddle.net/s61x7c4e/
Question was asked 5 years ago and I was dealing with smooth scroll and felt giving a simple solution is worth it to those who are looking for. All the answers are good but here you go a simple one.
function smoothScroll(){
document.querySelector('.your_class or #id here').scrollIntoView({
behavior: 'smooth'
});
}
just call the smoothScroll function on onClick event on your source element.
DOCS: https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollIntoView
Note: Please check compatibility here
3rd Party edit
Support for Element.scrollIntoView() in 2020 is this:
Region full + partial = sum full+partial Support
Asia 73.24% + 22.75% = 95.98%
North America 56.15% + 42.09% = 98.25%
India 71.01% + 20.13% = 91.14%
Europe 68.58% + 27.76% = 96.35%
Just made this javascript only solution below.
Simple usage:
EPPZScrollTo.scrollVerticalToElementById('signup_form', 20);
Engine object (you can fiddle with filter, fps values):
/**
*
* Created by Borbás Geri on 12/17/13
* Copyright (c) 2013 eppz! development, LLC.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
* The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
var EPPZScrollTo =
{
/**
* Helpers.
*/
documentVerticalScrollPosition: function()
{
if (self.pageYOffset) return self.pageYOffset; // Firefox, Chrome, Opera, Safari.
if (document.documentElement && document.documentElement.scrollTop) return document.documentElement.scrollTop; // Internet Explorer 6 (standards mode).
if (document.body.scrollTop) return document.body.scrollTop; // Internet Explorer 6, 7 and 8.
return 0; // None of the above.
},
viewportHeight: function()
{ return (document.compatMode === "CSS1Compat") ? document.documentElement.clientHeight : document.body.clientHeight; },
documentHeight: function()
{ return (document.height !== undefined) ? document.height : document.body.offsetHeight; },
documentMaximumScrollPosition: function()
{ return this.documentHeight() - this.viewportHeight(); },
elementVerticalClientPositionById: function(id)
{
var element = document.getElementById(id);
var rectangle = element.getBoundingClientRect();
return rectangle.top;
},
/**
* Animation tick.
*/
scrollVerticalTickToPosition: function(currentPosition, targetPosition)
{
var filter = 0.2;
var fps = 60;
var difference = parseFloat(targetPosition) - parseFloat(currentPosition);
// Snap, then stop if arrived.
var arrived = (Math.abs(difference) <= 0.5);
if (arrived)
{
// Apply target.
scrollTo(0.0, targetPosition);
return;
}
// Filtered position.
currentPosition = (parseFloat(currentPosition) * (1.0 - filter)) + (parseFloat(targetPosition) * filter);
// Apply target.
scrollTo(0.0, Math.round(currentPosition));
// Schedule next tick.
setTimeout("EPPZScrollTo.scrollVerticalTickToPosition("+currentPosition+", "+targetPosition+")", (1000 / fps));
},
/**
* For public use.
*
* #param id The id of the element to scroll to.
* #param padding Top padding to apply above element.
*/
scrollVerticalToElementById: function(id, padding)
{
var element = document.getElementById(id);
if (element == null)
{
console.warn('Cannot find element with id \''+id+'\'.');
return;
}
var targetPosition = this.documentVerticalScrollPosition() + this.elementVerticalClientPositionById(id) - padding;
var currentPosition = this.documentVerticalScrollPosition();
// Clamp.
var maximumScrollPosition = this.documentMaximumScrollPosition();
if (targetPosition > maximumScrollPosition) targetPosition = maximumScrollPosition;
// Start animation.
this.scrollVerticalTickToPosition(currentPosition, targetPosition);
}
};
Smooth scrolling - look ma no jQuery
Based on an article on itnewb.com i made a demo plunk to smoothly scroll without external libraries.
The javascript is quite simple. First a helper function to improve cross browser support to determine the current position.
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;
}
Then a function to determine the position of the destination element - the one where we would like to scroll to.
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;
}
And the core function to do the scrolling
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++;
}
return false;
}
To call it you just do the following. You create a link which points to another element by using the id as a reference for a destination anchor.
<a href="#anchor-2"
onclick="smoothScroll('anchor-2');">smooth scroll to the headline with id anchor-2<a/>
...
... some content
...
<h2 id="anchor-2">Anchor 2</h2>
Copyright
In the footer of itnewb.com the following is written: The techniques, effects and code demonstrated in ITNewb articles may be used for any purpose without attribution (although we recommend it) (2014-01-12)
You could also check this great Blog - with some very simple ways to achieve this :)
https://css-tricks.com/snippets/jquery/smooth-scrolling/
Like (from the blog)
// 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'
});
// Scroll to a certain element
document.querySelector('.hello').scrollIntoView({
behavior: 'smooth'
});
and you can also get the element "top" position like below (or some other way)
var e = document.getElementById(element);
var top = 0;
do {
top += e.offsetTop;
} while (e = e.offsetParent);
return top;
Why not use CSS scroll-behavior property
html {
scroll-behavior: smooth;
}
The browser support is also good
https://caniuse.com/#feat=css-scroll-behavior
For a more comprehensive list of methods for smooth scrolling, see my answer here.
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. To scroll to an element, just set the y-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:
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);
}
});
}
document.getElementById("toElement").addEventListener("click", function(e){
scrollToSmoothly(document.querySelector('div').offsetTop, 500 /* milliseconds */);
});
document.getElementById("backToTop").addEventListener("click", function(e){
scrollToSmoothly(0, 500);
});
<button id="toElement">Scroll To Element</button>
<div style="margin: 1000px 0px; text-align: center;">Div element
<button id="backToTop">Scroll back to top</button>
</div>
The SmoothScroll.js library can also be used, which supports scrolling to an element on the page in addition to more complex features such as smooth scrolling both vertically and horizontally, scrolling inside other container elements, different easing behaviors, scrolling relatively from the current position, and more.
document.getElementById("toElement").addEventListener("click", function(e){
smoothScroll({toElement: document.querySelector('div'), duration: 500});
});
document.getElementById("backToTop").addEventListener("click", function(e){
smoothScroll({yPos: 'start', duration: 500});
});
<script src="https://cdn.jsdelivr.net/gh/LieutenantPeacock/SmoothScroll#1.2.0/src/smoothscroll.min.js" integrity="sha384-UdJHYJK9eDBy7vML0TvJGlCpvrJhCuOPGTc7tHbA+jHEgCgjWpPbmMvmd/2bzdXU" crossorigin="anonymous"></script>
<button id="toElement">Scroll To Element</button>
<div style="margin: 1000px 0px; text-align: center;">Div element
<button id="backToTop">Scroll back to top</button>
</div>
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'
});
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'
});
I've been using this for a long time:
function scrollToItem(item) {
var diff=(item.offsetTop-window.scrollY)/8
if (Math.abs(diff)>1) {
window.scrollTo(0, (window.scrollY+diff))
clearTimeout(window._TO)
window._TO=setTimeout(scrollToItem, 30, item)
} else {
window.scrollTo(0, item.offsetTop)
}
}
usage:
scrollToItem(element) where element is document.getElementById('elementid') for example.
Variation of #tominko answer.
A little smoother animation and resolved problem with infinite invoked setTimeout(), when some elements can't allign to top of viewport.
function scrollToItem(item) {
var diff=(item.offsetTop-window.scrollY)/20;
if(!window._lastDiff){
window._lastDiff = 0;
}
console.log('test')
if (Math.abs(diff)>2) {
window.scrollTo(0, (window.scrollY+diff))
clearTimeout(window._TO)
if(diff !== window._lastDiff){
window._lastDiff = diff;
window._TO=setTimeout(scrollToItem, 15, item);
}
} else {
console.timeEnd('test');
window.scrollTo(0, item.offsetTop)
}
}
you can use this plugin. Does exactly what you want.
http://flesler.blogspot.com/2007/10/jqueryscrollto.html
If one need to scroll to an element inside a div there is my solution based on Andrzej Sala's answer:
function scroolTo(element, duration) {
if (!duration) {
duration = 700;
}
if (!element.offsetParent) {
element.scrollTo();
}
var startingTop = element.offsetParent.scrollTop;
var elementTop = element.offsetTop;
var dist = elementTop - startingTop;
var start;
window.requestAnimationFrame(function step(timestamp) {
if (!start)
start = timestamp;
var time = timestamp - start;
var percent = Math.min(time / duration, 1);
element.offsetParent.scrollTo(0, startingTop + dist * percent);
// Proceed with animation as long as we wanted it to.
if (time < duration) {
window.requestAnimationFrame(step);
}
})
}
Why not use this easy way
Native JS
document.querySelector(".layout").scrollIntoView({
behavior: "smooth",
});
Smooth scrolling with jQuery.ScrollTo
To use the jQuery ScrollTo plugin you have to do the following
Create links where href points to another elements.id
create the elements you want to scroll to
reference jQuery and the scrollTo Plugin
Make sure to add a click event handler for each link that should do smooth scrolling
Creating the links
<h1>Smooth Scrolling with the jQuery Plugin .scrollTo</h1>
<div id="nav-list">
Scroll to element 1
Scroll to element 2
Scroll to element 3
Scroll to element 4
</div>
Creating the target elements here only the first two are displayed the other headings are set up the same way. To see another example i added a link back to the navigation a.toNav
<h2 id="idElement1">Element1</h2>
....
<h2 id="idElement1">Element1</h2>
...
<a class="toNav" href="#nav-list">Scroll to Nav-List</a>
Setting the references to the scripts. Your path to the files may be different.
<script src="./jquery-1.8.3.min.js"></script>
<script src="./jquery.scrollTo-1.4.3.1-min.js"></script>
Wiring it all up
The code below is borrowed from jQuery easing plugin
jQuery(function ($) {
$.easing.elasout = function (x, t, b, c, d) {
var s = 1.70158; var p = 0; var a = c;
if (t == 0) return b;
if ((t /= d) == 1) return b + c;
if (!p) p = d * .3;
if (a < Math.abs(c)) {
a = c; var s = p / 4;
} else var s = p / (2 * Math.PI) * Math.asin(c / a);
// line breaks added to avoid scroll bar
return a * Math.pow(2, -10 * t) * Math.sin((t * d - s)
* (2 * Math.PI) / p) + c + b;
};
// important reset all scrollable panes to (0,0)
$('div.pane').scrollTo(0);
$.scrollTo(0); // Reset the screen to (0,0)
// adding a click handler for each link
// within the div with the id nav-list
$('#nav-list a').click(function () {
$.scrollTo(this.hash, 1500, {
easing: 'elasout'
});
return false;
});
// adding a click handler for the link at the bottom
$('a.toNav').click(function () {
var scrollTargetId = this.hash;
$.scrollTo(scrollTargetId, 1500, {
easing: 'elasout'
});
return false;
});
});
Fully working demo on plnkr.co
You may take a look at the soucre code for the demo.
Update May 2014
Based on another question i came across another solution from kadaj. Here jQuery animate is used to scroll to an element inside a <div style=overflow-y: scroll>
$(document).ready(function () {
$('.navSection').on('click', function (e) {
debugger;
var elemId = ""; //eg: #nav2
switch (e.target.id) {
case "nav1":
elemId = "#s1";
break;
case "nav2":
elemId = "#s2";
break;
case "nav3":
elemId = "#s3";
break;
case "nav4":
elemId = "#s4";
break;
}
$('.content').animate({
scrollTop: $(elemId).parent().scrollTop()
+ $(elemId).offset().top
- $(elemId).parent().offset().top
}, {
duration: 1000,
specialEasing: { width: 'linear'
, height: 'easeOutBounce' },
complete: function (e) {
//console.log("animation completed");
}
});
e.preventDefault();
});
});

How to prevent document scrolling but allow scrolling inside div elements on websites for iOS and Android?

I created a website with jQueryMobile for iOS and Android.
I don't want the document itself to scroll. Instead, just an area (a <div> element) should be scrollable (via css property overflow-y:scroll).
So I disabled document scrolling via:
$(document).bind("touchstart", function(e){
e.preventDefault();
});
$(document).bind("touchmove", function(e){
e.preventDefault();
});
But that will also disable scrolling for all other elements in the document, no matter if overflow:scroll is set or not.
How can I solve this?
How about this CSS only solution:
https://jsfiddle.net/Volker_E/jwGBy/24/
body gets position: fixed; and every other element you wish an overflow: scroll;.
Works on mobile Chrome (WebKit)/Firefox 19/Opera 12.
You'll also see my various attempts towards a jQuery solution. But as soon as you're binding touchmove/touchstart to document, it hinders scrolling in the child div no matter if unbinded or not.
Disclaimer: Solutions to this problem are in many ways basically not very nice UX-wise! You'll never know how big the viewport of your visitors exactly is or which font-size they are using (client user-agent style like), therefore it could easily be, that important content is hidden to them in your document.
Maybe I misunderstood the question, but if I'm correct:
You want not to be able to scroll except a certain element so you:
$(document).bind("touchmove", function(e){
e.preventDefault();
});
Prevent everything within the document.
Why don't you just stop the event bubbling on the element where you wish to scroll?
(PS: you don't have to prevent touchstart -> if you use touch start for selecting elements instead of clicks that is prevented as well, touch move is only needed because then it is actually tracing the movement)
$('#element').on('touchmove', function (e) {
e.stopPropagation();
});
Now on the element CSS
#element {
overflow-y: scroll; // (vertical)
overflow-x: hidden; // (horizontal)
}
If you are on a mobile device, you can even go a step further.
You can force hardware accelerated scrolling (though not all mobile browsers support this);
Browser Overflow scroll:
Android Browser Yes
Blackberry Browser Yes
Chrome for Mobile Yes
Firefox Mobile Yes
IE Mobile Yes
Opera Mini No
Opera Mobile Kinda
Safari Yes
#element.nativescroll {
-webkit-overflow-scrolling: touch;
}
normal:
<div id="element"></div>
native feel:
<div id="element" class="nativescroll"></div>
Finally, I got it to work. Really simple:
var $layer = $("#layer");
$layer.bind('touchstart', function (ev) {
var $this = $(this);
var layer = $layer.get(0);
if ($this.scrollTop() === 0) $this.scrollTop(1);
var scrollTop = layer.scrollTop;
var scrollHeight = layer.scrollHeight;
var offsetHeight = layer.offsetHeight;
var contentHeight = scrollHeight - offsetHeight;
if (contentHeight == scrollTop) $this.scrollTop(scrollTop-1);
});
Here is a solution I am using:
$scrollElement is the scroll element, $scrollMask is a div with style position: fixed; top: 0; bottom: 0;.
The z-index of $scrollMask is smaller than $scrollElement.
$scrollElement.on('touchmove touchstart', function (e) {
e.stopPropagation();
});
$scrollMask.on('touchmove', function(e) {
e.stopPropagation();
e.preventDefault();
});
I was looking for a solution that did not require calling out specific areas that should scroll. Piecing together a few resources, here is what worked for me:
// Detects if element has scroll bar
$.fn.hasScrollBar = function() {
return this.get(0).scrollHeight > this.outerHeight();
}
$(document).on("touchstart", function(e) {
var $scroller;
var $target = $(e.target);
// Get which element could have scroll bars
if($target.hasScrollBar()) {
$scroller = $target;
} else {
$scroller = $target
.parents()
.filter(function() {
return $(this).hasScrollBar();
})
.first()
;
}
// Prevent if nothing is scrollable
if(!$scroller.length) {
e.preventDefault();
} else {
var top = $scroller[0].scrollTop;
var totalScroll = $scroller[0].scrollHeight;
var currentScroll = top + $scroller[0].offsetHeight;
// If at container edge, add a pixel to prevent outer scrolling
if(top === 0) {
$scroller[0].scrollTop = 1;
} else if(currentScroll === totalScroll) {
$scroller[0].scrollTop = top - 1;
}
}
});
This code requires jQuery.
Sources:
this post
https://github.com/luster-io/prevent-overscroll
How can I check if a scrollbar is visible?
Jquery check if any parent div have scroll bar
Update
I needed a vanilla JavaScript version of this, so the following is a modified version. I implemented a margin-checker and something that explicitly allows input/textareas to be clickable (I was running into issues with this on the project I used it on...it may not be necessary for your project). Keep in mind this is ES6 code.
const preventScrolling = e => {
const shouldAllowEvent = element => {
// Must be an element that is not the document or body
if(!element || element === document || element === document.body) {
return false;
}
// Allow any input or textfield events
if(['INPUT', 'TEXTAREA'].indexOf(element.tagName) !== -1) {
return true;
}
// Get margin and outerHeight for final check
const styles = window.getComputedStyle(element);
const margin = parseFloat(styles['marginTop']) +
parseFloat(styles['marginBottom']);
const outerHeight = Math.ceil(element.offsetHeight + margin);
return (element.scrollHeight > outerHeight) && (margin >= 0);
};
let target = e.target;
// Get first element to allow event or stop
while(target !== null) {
if(shouldAllowEvent(target)) {
break;
}
target = target.parentNode;
}
// Prevent if no elements
if(!target) {
e.preventDefault();
} else {
const top = target.scrollTop;
const totalScroll = target.scrollHeight;
const currentScroll = top + target.offsetHeight;
// If at container edge, add a pixel to prevent outer scrolling
if(top === 0) {
target.scrollTop = 1;
} else if(currentScroll === totalScroll) {
target.scrollTop = top - 1;
}
}
};
document.addEventListener('touchstart', preventScrolling);
document.addEventListener('mousedown', preventScrolling);
In my case, I have a scrollable body and a scrollable floating menu over it. Both have to be scrollable, but I had to prevent body scrolling when "floating menu" (position:fixed) received touch events and was scrolling and it reached top or bottom. By default browser then started to scroll the body.
I really liked jimmont's answer, but unfortunatelly it did not work well on all devices and browsers, especially with a fast and long swipe.
I ended up using MOMENTUM SCROLLING USING JQUERY (hnldesign.nl) on floating menu, which prevents default browser scrolling and then animates scrolling itself. I include that code here for completeness:
/**
* jQuery inertial Scroller v1.5
* (c)2013 hnldesign.nl
* This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/4.0/.
**/
/*jslint browser: true*/
/*global $, jQuery*/
/* SETTINGS */
var i_v = {
i_touchlistener : '.inertialScroll', // element to monitor for touches, set to null to use document. Otherwise use quotes. Eg. '.myElement'. Note: if the finger leaves this listener while still touching, movement is stopped.
i_scrollElement : '.inertialScroll', // element (class) to be scrolled on touch movement
i_duration : window.innerHeight * 1.5, // (ms) duration of the inertial scrolling simulation. Devices with larger screens take longer durations (phone vs tablet is around 500ms vs 1500ms). This is a fixed value and does not influence speed and amount of momentum.
i_speedLimit : 1.2, // set maximum speed. Higher values will allow faster scroll (which comes down to a bigger offset for the duration of the momentum scroll) note: touch motion determines actual speed, this is just a limit.
i_handleY : true, // should scroller handle vertical movement on element?
i_handleX : true, // should scroller handle horizontal movement on element?
i_moveThreshold : 100, // (ms) determines if a swipe occurred: time between last updated movement # touchmove and time # touchend, if smaller than this value, trigger inertial scrolling
i_offsetThreshold : 30, // (px) determines, together with i_offsetThreshold if a swipe occurred: if calculated offset is above this threshold
i_startThreshold : 5, // (px) how many pixels finger needs to move before a direction (horizontal or vertical) is chosen. This will make the direction detection more accurate, but can introduce a delay when starting the swipe if set too high
i_acceleration : 0.5, // increase the multiplier by this value, each time the user swipes again when still scrolling. The multiplier is used to multiply the offset. Set to 0 to disable.
i_accelerationT : 250 // (ms) time between successive swipes that determines if the multiplier is increased (if lower than this value)
};
/* stop editing here */
//set some required vars
i_v.i_time = {};
i_v.i_elem = null;
i_v.i_elemH = null;
i_v.i_elemW = null;
i_v.multiplier = 1;
// Define easing function. This is based on a quartic 'out' curve. You can generate your own at http://www.timotheegroleau.com/Flash/experiments/easing_function_generator.htm
if ($.easing.hnlinertial === undefined) {
$.easing.hnlinertial = function (x, t, b, c, d) {
"use strict";
var ts = (t /= d) * t, tc = ts * t;
return b + c * (-1 * ts * ts + 4 * tc + -6 * ts + 4 * t);
};
}
$(i_v.i_touchlistener || document)
.on('touchstart touchmove touchend', function (e) {
"use strict";
//prevent default scrolling
e.preventDefault();
//store timeStamp for this event
i_v.i_time[e.type] = e.timeStamp;
})
.on('touchstart', function (e) {
"use strict";
this.tarElem = $(e.target);
this.elemNew = this.tarElem.closest(i_v.i_scrollElement).length > 0 ? this.tarElem.closest(i_v.i_scrollElement) : $(i_v.i_scrollElement).eq(0);
//dupecheck, optimizes code a bit for when the element selected is still the same as last time
this.sameElement = i_v.i_elem ? i_v.i_elem[0] == this.elemNew[0] : false;
//no need to redo these if element is unchanged
if (!this.sameElement) {
//set the element to scroll
i_v.i_elem = this.elemNew;
//get dimensions
i_v.i_elemH = i_v.i_elem.innerHeight();
i_v.i_elemW = i_v.i_elem.innerWidth();
//check element for applicable overflows and reevaluate settings
this.i_scrollableY = !!((i_v.i_elemH < i_v.i_elem.prop('scrollHeight') && i_v.i_handleY));
this.i_scrollableX = !!((i_v.i_elemW < i_v.i_elem.prop('scrollWidth') && i_v.i_handleX));
}
//get coordinates of touch event
this.pageY = e.originalEvent.touches[0].pageY;
this.pageX = e.originalEvent.touches[0].pageX;
if (i_v.i_elem.is(':animated') && (i_v.i_time.touchstart - i_v.i_time.touchend) < i_v.i_accelerationT) {
//user swiped while still animating, increase the multiplier for the offset
i_v.multiplier += i_v.i_acceleration;
} else {
//else reset multiplier
i_v.multiplier = 1;
}
i_v.i_elem
//stop any animations still running on element (this enables 'tap to stop')
.stop(true, false)
//store current scroll positions of element
.data('scrollTop', i_v.i_elem.scrollTop())
.data('scrollLeft', i_v.i_elem.scrollLeft());
})
.on('touchmove', function (e) {
"use strict";
//check if startThreshold is met
this.go = (Math.abs(this.pageX - e.originalEvent.touches[0].pageX) > i_v.i_startThreshold || Math.abs(this.pageY - e.originalEvent.touches[0].pageY) > i_v.i_startThreshold);
})
.on('touchmove touchend', function (e) {
"use strict";
//check if startThreshold is met
if (this.go) {
//set animpar1 to be array
this.animPar1 = {};
//handle events
switch (e.type) {
case 'touchmove':
this.vertical = Math.abs(this.pageX - e.originalEvent.touches[0].pageX) < Math.abs(this.pageY - e.originalEvent.touches[0].pageY); //find out in which direction we are scrolling
this.distance = this.vertical ? this.pageY - e.originalEvent.touches[0].pageY : this.pageX - e.originalEvent.touches[0].pageX; //determine distance between touches
this.acc = Math.abs(this.distance / (i_v.i_time.touchmove - i_v.i_time.touchstart)); //calculate acceleration during movement (crucial)
//determine which property to animate, reset animProp first for when no criteria is matched
this.animProp = null;
if (this.vertical && this.i_scrollableY) { this.animProp = 'scrollTop'; } else if (!this.vertical && this.i_scrollableX) { this.animProp = 'scrollLeft'; }
//set animation parameters
if (this.animProp) { this.animPar1[this.animProp] = i_v.i_elem.data(this.animProp) + this.distance; }
this.animPar2 = { duration: 0 };
break;
case 'touchend':
this.touchTime = i_v.i_time.touchend - i_v.i_time.touchmove; //calculate touchtime: the time between release and last movement
this.i_maxOffset = (this.vertical ? i_v.i_elemH : i_v.i_elemW) * i_v.i_speedLimit; //(re)calculate max offset
//calculate the offset (the extra pixels for the momentum effect
this.offset = Math.pow(this.acc, 2) * (this.vertical ? i_v.i_elemH : i_v.i_elemW);
this.offset = (this.offset > this.i_maxOffset) ? this.i_maxOffset : this.offset;
this.offset = (this.distance < 0) ? -i_v.multiplier * this.offset : i_v.multiplier * this.offset;
//if the touchtime is low enough, the offset is not null and the offset is above the offsetThreshold, (re)set the animation parameters to include momentum
if ((this.touchTime < i_v.i_moveThreshold) && this.offset !== 0 && Math.abs(this.offset) > (i_v.i_offsetThreshold)) {
if (this.animProp) { this.animPar1[this.animProp] = i_v.i_elem.data(this.animProp) + this.distance + this.offset; }
this.animPar2 = { duration: i_v.i_duration, easing : 'hnlinertial', complete: function () {
//reset multiplier
i_v.multiplier = 1;
}};
}
break;
}
// run the animation on the element
if ((this.i_scrollableY || this.i_scrollableX) && this.animProp) {
i_v.i_elem.stop(true, false).animate(this.animPar1, this.animPar2);
}
}
});
Another observation: I also tried various combinations of e.stopPropagation() on menu div and e.preventDefault() on window/body at touchmove event, but without success, I only managed to prevent scrolling I wanted and not scrolling I did not want. I also tried to have a div over whole document, with z-index between document and menu, visible only between touchstart and touchend, but it did not receive touchmove event (because it was under menu div).
Here is a solution that uses jQuery for the events.
var stuff = {};
$('#scroller').on('touchstart',stuff,function(e){
e.data.max = this.scrollHeight - this.offsetHeight;
e.data.y = e.originalEvent.pageY;
}).on('touchmove',stuff,function(e){
var dy = e.data.y - e.originalEvent.pageY;
// if scrolling up and at the top, or down and at the bottom
if((dy < 0 && this.scrollTop < 1)||(dy > 0 && this.scrollTop >= e.data.max)){
e.preventDefault();
};
});
First position the innerScroller wherever you want on the screen and then fix outerScroller by setting it css to 'hidden'. When you want to restore it you can set it back to 'auto' or 'scroll', whichever you used previously.
Here is my implementation which works on touch devices and laptops.
function ScrollManager() {
let startYCoord;
function getScrollDiff(event) {
let delta = 0;
switch (event.type) {
case 'mousewheel':
delta = event.wheelDelta ? event.wheelDelta : -1 * event.deltaY;
break;
case 'touchstart':
startYCoord = event.touches[0].clientY;
break;
case 'touchmove': {
const yCoord = event.touches[0].clientY;
delta = yCoord - startYCoord;
startYCoord = yCoord;
break;
}
}
return delta;
}
function getScrollDirection(event) {
return getScrollDiff(event) >= 0 ? 'UP' : 'DOWN';
}
function blockScrollOutside(targetElement, event) {
const { target } = event;
const isScrollAllowed = targetElement.contains(target);
const isTouchStart = event.type === 'touchstart';
let doScrollBlock = !isTouchStart;
if (isScrollAllowed) {
const isScrollingUp = getScrollDirection(event) === 'UP';
const elementHeight = targetElement.scrollHeight - targetElement.offsetHeight;
doScrollBlock =
doScrollBlock &&
((isScrollingUp && targetElement.scrollTop <= 0) ||
(!isScrollingUp && targetElement.scrollTop >= elementHeight));
}
if (doScrollBlock) {
event.preventDefault();
}
}
return {
blockScrollOutside,
getScrollDirection,
};
}
const scrollManager = ScrollManager();
const testBlock = document.body.querySelector('.test');
function handleScroll(event) {
scrollManager.blockScrollOutside(testBlock, event);
}
window.addEventListener('scroll', handleScroll);
window.addEventListener('mousewheel', handleScroll);
window.addEventListener('touchstart', handleScroll);
window.addEventListener('touchmove', handleScroll);
.main {
border: 1px solid red;
height: 200vh;
}
.test {
border: 1px solid green;
height: 300px;
width: 300px;
overflow-y: auto;
position: absolute;
top: 100px;
left: 50%;
}
.content {
height: 100vh;
}
<div class="main">
<div class="test">
<div class="content"></div>
</div>
</div>
This is what worked for me for Android and IOS devices.
Imagine that we have a div class="backdrop"> element that we don't want to be scrolled, ever. But we want to be able to scroll over an element that is on top of this backdrop.
function handleTouchMove(event) {
const [backdrop] = document.getElementsByClassName('backdrop');
const isScrollingBackdrop = backdrop === event.target;
isScrollingBackdrop ? event.preventDefault() : event.stopPropagation();
}
window.addEventListener('touchmove', handleTouchMove, { passive: false });
So, we listen to the touchmove event, if we're scrolling over the backdrop, we prevent it. If we're scrolling over something else, we allow it but stop its propagation so it doesn't scroll also the backdrop.
Of course this is pretty basic and can be re-worked and expanded a lot, but this is what fixed my issue in a VueJs2 project.
Hope it helps! ;)
I was able to disable scrolling of the main document by adding css "overflow-y: hidden" on HTML.
It did not mess with positioning at all.

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();
};
});
}
}
});
`

scroll page so that element is visible

I've just tried prototype's scrollTo function and as the documentation states, it
Scrolls the window so that element
appears at the top of the viewport
I'd like a function that
only scrolls if the element is not entirely visible within the viewport
scrolls so that the element appears at the center of the viewport
does anyone know of such a function in prototype, scriptaculous or stand-alone?
I guess you need something like this (demo):
window.height
function getWindowHeight() {
var body = document.body;
var docEl = document.documentElement;
return window.innerHeight ||
(docEl && docEl.clientHeight) ||
(body && body.clientHeight) ||
0;
}
Scroll
function scrollElemToCenter(id, duration) {
var el = document.getElementById(id);
var winHeight = getWindowHeight();
var offsetTop = el.offsetTop;
if (offsetTop > winHeight) {
var y = offsetTop - (winHeight-el.offsetHeight)/2;
// wo animation: scrollTo(0, y);
scrollToAnim(y, duration);
}
}
Animation (optional, you can use script.aculo.us, etc.)
function interpolate(source,target,pos) { return (source+(target-source)*pos); }
function easing(pos) { return (-Math.cos(pos*Math.PI)/2) + 0.5; }
function scrollToAnim(targetTop, duration) {
duration || (duration = 1000);
var start = +new Date,
finish = start + duration,
startTop = getScrollRoot().scrollTop,
interval = setInterval(function(){
var now = +new Date,
pos = (now>finish) ? 1 : (now-start)/duration;
var y = interpolate(startTop, targetTop, easing(pos)) >> 0;
window.scrollTo(0, y);
if(now > finish) {
clearInterval(interval);
}
}, 10);
}
get scroll root
var getScrollRoot = (function() {
var SCROLL_ROOT;
return function() {
if (!SCROLL_ROOT) {
var bodyScrollTop = document.body.scrollTop;
var docElScrollTop = document.documentElement.scrollTop;
window.scrollBy(0, 1);
if (document.body.scrollTop != bodyScrollTop)
(SCROLL_ROOT = document.body);
else
(SCROLL_ROOT = document.documentElement);
window.scrollBy(0, -1);
}
return SCROLL_ROOT;
};
})();
Here is an alternative approach, that uses some of Prototype's built in functionality for working with the viewport and scroll dimensions...
function scrollToCenterOfElement(id){
// Cache element and property lookups...
var element = $(id);
var height = element.measure('height');
var top = element.cumulativeOffset().top;
var scroll = document.viewport.getScrollOffsets();
var dimensions = document.viewport.getDimensions();
// Checks to see if the top offset plus the height of the element is greater
// than the sum of the viewport height and vertical scroll offset, which means
// that the element has yet to be fully scrolled in to view, or if the
// top offset is smaller than the vertical scroll offset, which means the element
// has already been (at least partly) scrolled out of view..
if ((top + height > dimensions.height + scroll.top) || (top < dimensions.height + scroll.top)) {
// Scroll window to sum of top offset plus half the height of the element
// minus half of the viewport height, thus centering the element vertically.
window.scrollTo(0, top + (height / 2) - (dimensions.height / 2));
}
}
scrollToCenterOfElement('my-element');
My solution does not cover 100% of what is requested, but perhaps someone finds it useful.
/**
* Scroll container so that given element becomes visible. Features:
* <ol>
* <li>If element is already visible, then no action is taken.
* <li>If element is above view port, the viewport is scrolled upwards so that element becomes visible at the top.
* <li>If element is below view port, the viewport is scrolled downwards so that element becomes visible at the bottom.
* </ol>
*
* #param element
* optional string (selector) or jQuery object that controls the scrolling of the element
* #param options
* optional extra settings
* #param options.animationSpeed
* if defined, then scrolling is animated; determines time in milliseconds after which the element should
* be scrolled into viewport
* #param options.heightScale
* double number from 0 to 1; when scrolling the element from bottom sometimes it is desirable to scroll
* element close to the top; e.g. to scroll it to the center specify 0.5; to scroll it to the top specify 0
* #param options.complete
* function to be called after animation is completed; if there is no animation, the function is called straight away
*/
$.fn.scrollTo = function(element, options) {
options = options || {};
var elementTop = element.offset().top;
var containerTop = this.offset().top;
var newScrollTop = null;
if (elementTop < containerTop) {
// Scroll to the top:
newScrollTop = Math.round(this.scrollTop() + elementTop - containerTop);
} else {
// Scroll to the bottom:
var elementBottom = elementTop + element.outerHeight(true);
var containerHeight = this.height();
if (elementBottom > containerTop + containerHeight) {
if (options.heightScale != null) {
if (options.heightScale === 0) {
// This will effectively turn the formulae below into "elementTop - containerTop":
containerHeight = element.outerHeight(true);
} else {
containerHeight *= options.heightScale;
}
}
newScrollTop = Math.round(this.scrollTop() + elementBottom - containerTop - containerHeight);
}
}
if (newScrollTop !== null) {
if (options && options.animationSpeed) {
this.animate({
scrollTop : newScrollTop
}, {
"duration" : options.animationSpeed,
"complete" : options.complete
});
} else {
this.scrollTop(newScrollTop);
if ($.isFunction(options.complete)) {
options.complete();
}
}
} else {
if ($.isFunction(options.complete)) {
options.complete();
}
}
return this;
};
Demo

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