position: sticky works on some mobile browsers now, so you can make a menu bar scroll with the page but then stick to the top of the viewport whenever the user scrolls past it.
But what if you want to restyle your sticky menu bar slightly whenever it's currently 'sticking'? eg, you might want the bar to have rounded corners whenever it's scrolling with the page, but then as soon as it sticks to the top of the viewport, you want to get rid of the top rounded corners, and add a little drop shadow underneath it.
Is there any kind of pseudoselector (eg ::stuck) to target elements that have position: sticky and are currently sticking? Or do browser vendors have anything like this in the pipeline? If not, where would I request it?
NB. javascript solutions are not good for this because on mobile you usually only get a single scroll event when the user releases their finger, so JS can't know the exact moment that the scroll threshold was passed.
There is currently no selector that is being proposed for elements that are currently 'stuck'. The Postioned Layout module where position: sticky is defined does not mention any such selector either.
Feature requests for CSS can be posted to the www-style mailing list. I believe a :stuck pseudo-class makes more sense than a ::stuck pseudo-element, since you're looking to target the elements themselves while they are in that state. In fact, a :stuck pseudo-class was discussed some time ago; the main complication, it was found, is one that plagues just about any proposed selector that attempts to match based on a rendered or computed style: circular dependencies.
In the case of a :stuck pseudo-class, the simplest case of circularity would occur with the following CSS:
:stuck { position: static; /* Or anything other than sticky/fixed */ }
:not(:stuck) { position: sticky; /* Or fixed */ }
And there could be many more edge cases that would be difficult to address.
While it's generally agreed upon that having selectors that match based on certain layout states would be nice, unfortunately major limitations exist that make these non-trivial to implement. I wouldn't hold my breath for a pure CSS solution to this problem anytime soon.
In some cases a simple IntersectionObserver can do the trick, if the situation allows for sticking to a pixel or two outside its root container, rather than properly flush against. That way when it sits just beyond the edge, the observer fires and we're off and running.
const observer = new IntersectionObserver(
([e]) => e.target.toggleAttribute('stuck', e.intersectionRatio < 1),
{threshold: [1]}
);
observer.observe(document.querySelector('nav'));
Stick the element just out of its container with top: -2px, and then target via the stuck attribute...
nav {
background: magenta;
height: 80px;
position: sticky;
top: -2px;
}
nav[stuck] {
box-shadow: 0 0 16px black;
}
Example here: https://codepen.io/anon/pen/vqyQEK
I wanted a pure CSS solution that would allow styling a 'stuck' element, as though a ::stuck pseudo-selector exists (alas, still not in 2021).
I have created a pure CSS hack that achieves the effect with no JS and fits my needs. It works by having two copies of the element, one is sticky and the other isn't (unstuck one), and this latter one covers up the sticky element until you scroll by it.
Demo: https://codepen.io/TomAnthony/pen/qBqgErK
Alternative demo: https://codepen.io/TomAnthony/pen/mdOvJYw (this version is more what I wanted, I wanted the sticky items to only appear once they were 'stuck' - it also means no duplicate content.)
HTML:
<div class="sticky">
<div class="unstuck">
<div>
Box header. Italic when 'stuck'.
</div>
</div>
<div class="stuck">
<div>
Box header. Italic when 'stuck'.
</div>
</div>
</div>
CSS:
.sticky {
height: 20px;
display: inline;
background-color: pink;
}
.stuck {
position: -webkit-sticky;
position: sticky;
top: 0;
height: 20px;
font-style: italic;
}
.unstuck {
height: 0;
overflow-y: visible;
position: relative;
z-index: 1;
}
.unstuck > div {
position: absolute;
width: 100%;
height: 20px;
background-color: inherit;
}
Someone on the Google Developers blog claims to have found a performative JavaScript-based solution with an IntersectionObserver.
Relevant code bit here:
/**
* Sets up an intersection observer to notify when elements with the class
* `.sticky_sentinel--top` become visible/invisible at the top of the container.
* #param {!Element} container
*/
function observeHeaders(container) {
const observer = new IntersectionObserver((records, observer) => {
for (const record of records) {
const targetInfo = record.boundingClientRect;
const stickyTarget = record.target.parentElement.querySelector('.sticky');
const rootBoundsInfo = record.rootBounds;
// Started sticking.
if (targetInfo.bottom < rootBoundsInfo.top) {
fireEvent(true, stickyTarget);
}
// Stopped sticking.
if (targetInfo.bottom >= rootBoundsInfo.top &&
targetInfo.bottom < rootBoundsInfo.bottom) {
fireEvent(false, stickyTarget);
}
}
}, {threshold: [0], root: container});
// Add the top sentinels to each section and attach an observer.
const sentinels = addSentinels(container, 'sticky_sentinel--top');
sentinels.forEach(el => observer.observe(el));
}
I haven't replicated it myself, but maybe it helps someone stumbling over this question.
Not really a fan of using js hacks for styling stuff (ie getBoudingClientRect, scroll listening, resize listening), but this is how I'm currently solving the problem. This solution will have issues with pages that have minimizable/maximizable content (<details>), or nested scrolling, or really any curve balls whatsoever. That being said, it's a simple solution for when the problem is simple as well.
let lowestKnownOffset: number = -1;
window.addEventListener("resize", () => lowestKnownOffset = -1);
const $Title = document.getElementById("Title");
let requestedFrame: number;
window.addEventListener("scroll", (event) => {
if (requestedFrame) { return; }
requestedFrame = requestAnimationFrame(() => {
// if it's sticky to top, the offset will bottom out at its natural page offset
if (lowestKnownOffset === -1) { lowestKnownOffset = $Title.offsetTop; }
lowestKnownOffset = Math.min(lowestKnownOffset, $Title.offsetTop);
// this condition assumes that $Title is the only sticky element and it sticks at top: 0px
// if there are multiple elements, this can be updated to choose whichever one it furthest down on the page as the sticky one
if (window.scrollY >= lowestKnownOffset) {
$Title.classList.add("--stuck");
} else {
$Title.classList.remove("--stuck");
}
requestedFrame = undefined;
});
})
A compact way for when you have an element above the position:sticky element. It sets the attribute stuck which you can match in CSS with header[stuck]:
HTML:
<img id="logo" ...>
<div>
<header style="position: sticky">
...
</header>
...
</div>
JS:
if (typeof IntersectionObserver !== 'function') {
// sorry, IE https://caniuse.com/#feat=intersectionobserver
return
}
new IntersectionObserver(
function (entries, observer) {
for (var _i = 0; _i < entries.length; _i++) {
var stickyHeader = entries[_i].target.nextSibling
stickyHeader.toggleAttribute('stuck', !entries[_i].isIntersecting)
}
},
{}
).observe(document.getElementById('logo'))
So I am a bit stumped on this ... I'm using a WebView in a portion of our app, the reason for the WebView is because we are pulling from an API endpoint that returns to us an HTML string. The font size and other things in this HTML string aren't styled for the purpose of using in a mobile app so we are trying to add some stylistic changes to it for better viewability. I've seen people add Style Tags at the top of the html file to add specific html styles to the element, and everything is generally working except the font size in the HTML of WebView renders differently every time I click into the screen that has the WebView contained in it.
Here is the current code (style + html + script):
let rawHTML = htmlStyle + this.props.itemDetails.body_html.replace("\n", "").replace(/("\/\/[c])\w/g, "\"https://cd").replace(/(width: 10.094%;)/g, "").replace(/(width: 84.906%;)/g, "") + heightScript
I have also console logged this string out in the debugger to make sure it's stitched well, and have even created and index.html and pasted in there the exact string, to make sure it's just showing up properly there.
Here is the style string:
let htmlStyle = `<style>
#height-calculator {
margin: 0;
padding: 0;
}
#height-calculator {
position: absolute;
top: 0;
left: 0;
right: 0;
margin: 0;
padding: 0;
}
body {
width:100%;
}
h2 {
font-size: 48px;
}
p {
font-size: 18px;
}
h3 {
font-size: 32px
}
img {
width:98%;
}
td {
display: block !important;
width: 95% !important;
}
img {
width:98%;
}
hr {
width: 98%;
}
ol li ol li ol li {
position: relative; right: 85px;
}
ul {
width: 98%,
margin-left: -25px;
}
li {
width: 98%;
}
.tabs {
display: none;
}
.tabs > li {
display: none;
}
.tabs-content {
padding: 0;
list-style-type: none;
}
tr {
display: flex;
flex-direction: column;
}
</style>`
And finally here is the WebView:
<WebView
javaScriptEnabled={true}
onNavigationStateChange={this.onNavigationStateChange.bind(this)}
scrollEnabled={false}
source={{html: rawHTML}}
style={{height: Number(this.state.height)}}
domStorageEnabled={true}
scalesPageToFit={true}
decelerationRate="normal"
javaScriptEnabledAndroid={true} />
Also, as I mentioned all the other styles applied are working, it's mainly just the font size that is super unpredictable.
Here is the view when I click it one time:
And then I don't change or exit the app, I just go back, and then click the same button to enter that same display and I get this sometimes (it sometimes takes multiple clicks ... it's very unpredictable):
I have a video of this as well, if you feel that would help this explanation. I'm trying to retell it the best I can haha.
Edit:
I think this might be a simulator only related issue? If anyone could speak some wisdom into that, that would be awesome still. I can't seem to reproduce this error on production build.
I recently experienced the same issue. It was only occurring for me on iOS, not Android.
The weirdest part is the inconsistency in replication. I couldn't find any pattern to when the WebView content would be sized differently. Identical HTML would result in font size that was sometimes normal, but other times very tiny.
My solution came from a (RN 0.47) WebView prop:
scalesPageToFit?: bool
Boolean that controls whether the web content is scaled to fit the view and enables the user to change the scale. The default value is true.
I tried setting scalesPageToFit to false, and voilà, the page stopped scaling down:
<WebView
source={{ html: myHtml }}
scalesPageToFit={false}
/>
The only problem is that this caused my content to be scaled larger than the WebView's container on Android. To fix this, I simply set the scalesPageToFit prop conditionally, based on platform:
<WebView
source={{ html: myHtml }}
scalesPageToFit={(Platform.OS === 'ios') ? false : true}
/>
Worked like a charm for me!
I used react-native-render-html. The reason I choose this solution over the accepted answer is because I can style html tags using react native styles instead of injecting style declaration string before the actual content.
const htmlStyles = { p: {fontFamily: 'Lato'} }
const htmlContent = <H1>My Html</H1>;
<HTML containerStyle={ {margin: 16} }
html={ htmlContent }
tagsStyles={ htmlStyles } />
I'm curious to the behaviour of using calc() in setting a CSS variable.
Example:
#test {
--halfWidth: calc(100% / 2);
}
Now, if the #test element, say a div, was 500px wide, I would like the --halfWidth variable to be set to 250px.
But, as far as I can tell the var(--halfWidth) code used elsewhere simply drops in the calc(100% / 2) string instead of 250px. Which means that I can't use the calculation of say element A and use it in element B later on, since it would simply set for example width: var(--halfWidth); as half the width of element B instead of half the width of element A, where the variable was defined.
I've scoured the web trying to find any documentation on the behaviour of this, but I have so far drawn a blank.
Ideally, setting a CSS variable using calc should be available in two variants:
One variant working just like this example, simply dropping in the string as-is, bar any in-string variable replacements.
A second variant where calc() would yield the result of the calculation instead of simply replacing the string.
How to achieve this? I'd rather leave the actual implementation to people suited to it, but one possibility would be an eval() kind of thing; like eval(calc(100% / 2)) would give the result 250px.
Anyway, if anyone have any real documentation on this behaviour or a solution to how to get the example above to yield the result instead, I'm all ears!
Edit: Just FYI, I have read the specs at https://drafts.csswg.org/css-variables/
This is kind of a tough question to answer cause the answer will not be:
Do it like this...then it will work
The problem you are facing is the normal behavior of CSS. It cascades the styles. If what you are trying to achieve would work it would get real messy after a short amount of time.
I mean how cool is it that you can define a variable like this
#test {
--halfWidth: calc(100% / 2);
}
where var(--halfWidth) should always be calc(100% / 2). Did you note that it will always be half the width of the parent element?
Imagine how strange it would be if a programmer in a few months reads your code and has box with a width of 1000px set with --halfWidth and now it is 250px wide ... I would think the internet is broken :) It should just be 500px wide.
To achieve what you want, you could/should define different vars defining the widths of the parent elements. And split it down to the children.
One approach to this is to dynamically add a line to the CSS Object Model (CSSOM) which explicitly declares the width of the .halfwidth class.
This width will then apply to all divs with the .halfwidth class.
In the example below, I have, additionally, made .element-a horizontally resizable, so that you can see more clearly that as you change the width of .element-a, the width of both .halfwidth divs changes proportionately, including the .halfwidth div which is a child of .element-b.
Working Example:
let myStylesheet = document.styleSheets[0];
const elementA = document.getElementsByClassName('element-a')[0];
let elementAWidth = window.getComputedStyle(elementA).getPropertyValue('width');
const calculateHalfWidth = (elementAWidth) => {
myStylesheet.insertRule('.halfWidth { width: ' + (parseInt(elementAWidth) / 2) + 'px; }', myStylesheet.cssRules.length);
}
calculateHalfWidth(elementAWidth);
// ================================================================================
// THE SCRIPT BELOW USES A ResizeObserver TO WATCH THE RESIZABLE .element-a DIV
// ================================================================================
const elementAObserver = new ResizeObserver(entries => {
for (let entry of entries) {
if (entry.contentRect.width !== elementAWidth) {
calculateHalfWidth(entry.contentRect.width);
}
}
});
elementAObserver.observe(elementA);
body {
font-family: sans-serif;
}
div.element {
float: left;
width: 200px;
height: 100px;
margin: 12px 3px;
text-align: center;
border: 1px solid rgb(0, 0, 0);
}
div.element h2 {
font-size: 18px;
}
div.element-a {
resize: horizontal;
overflow: auto;
}
div.element-b {
width: 300px;
}
div.halfWidth {
height: 40px;
margin: 0 auto;
border: 1px dashed rgb(255, 0, 0);
}
div.halfWidth h2 {
font-size: 14px;
}
<div class="element element-a">
<h2>Element A</h2>
<div class="halfWidth">
<h2>halfWidth</h2>
</div>
</div>
<div class="element element-b">
<h2>Element B</h2>
<div class="halfWidth">
<h2>halfWidth</h2>
</div>
</div>
I'm wondering if there's a way to fade out (like a gradient) the opacity of an iframe and the content inside it. It's difficult to explain so a common example would be at the bottom of notification centre on Mountain Lion or iOs.
The whole idea is that when a user scrolls down (in an iframe) the content "fades out" at the bottom and it doesn't cut off with a straight line.
Not sure if this is possible with CSS or Javascript.
Any help is greatly appreciated. Thanks
If I've understood you correctly, you want something like this:
https://dl.dropbox.com/u/73603348/fadeout.html
What I've done in the past is create an overlay element at the bottom of the scrolling content. Pretty simple.
The markup:
<div class="content">
<div class="container">
[ content here ]
</div>
<div class="fader"></div>
</div>
The style:
.content {
width: 600px;
background: #fff;
margin: 50px auto 0;
overflow: auto;
position: relative;
}
.container {
height: 500px;
overflow: auto;
padding: 10px;
background: #ccc;
}
.fader {
position: absolute;
content: '';
bottom: 0;
left: 0;
right: 0;
height: 100px;
background: -webkit-linear-gradient(top, rgba(255,255,255,0), #fff);
}
Just in case you don't want to load the whole jQuery library, you can write your own function to do the fadeout. Here's my own try to write such a function:
var ifrm = document.getElementById("your_frame"); //find your frame
function fadeOut(var duration) { //duration: how many millseconds you want the effect to take
var step = 10 / duration; //step is how much the opacity will change each 10 milliseconds
var curOpacity = 1; //at first the iframe is fully opaque.
function animate() {
if(curOpacity < step) {
ifrm.style.opacity = 0; //we're done
return;
}
ifrm.style.opacity = curOpacity;
curOpacity -= step;
setTimeout(animate, 10); //wait 10 millseconds and move to next step of animation
}
animate();
}
So suppose you want to fadeout for 1 second, then the initial fadeOut function call would be: fadeOut(1000);.
Again, I hope that helped you.
You can use jQuery. Example on how to fade out an element:
$("#your_iframe_id").fadeOut();
More details on how to use fadeOut: jQuery API reference about fadeOut.
I've been searching for a "lightbox" type solution that allows this but haven't found one yet (please, suggest if you know of any).
The behavior I'm trying to recreate is just like what you'd see at Pinterest when clicking on an image. The overlay is scrollable (as in the whole overlay moves up like a page on top of a page) but the body behind the overlay is fixed.
I attempted to create this with just CSS (i.e. a div overlay on top of the whole page and body with overflow: hidden), but it doesn't prevent div from being scrollable.
How to keep the body/page from scrolling but keep scrolling inside the fullscreen container?
Theory
Looking at current implementation of the pinterest site (it might change in the future), when you open the overlay, a noscroll class is applied to the body element (setting overflow: hidden) making the body no longer scrollable.
The overlay created on-the-fly or already injected in the page and made visible via display: block — it makes no difference – has position : fixed and overflow-y: scroll, with top, left, right and bottom properties set to 0: this style makes the overlay fill the whole viewport (but now we are in 2022, so you may use inset: 0 instead).
The div inside the overlay is in position: static so the vertical scrollbar is related to that element. This is resulting in a scrollable but fixed overlay.
When you close the overlay, you have to hide it (using display: none) and you could even remove the node via javascript (or just the content inside, it's up to you but also depends on the nature of the content).
The final step is to also remove the noscroll class applied to the body (so the overflow property gets back to the value it had previously)
Code
Codepen Example
(it works by changing the aria-hidden attribute of the overlay in order to show and hide it and to increase its accessibility).
Markup
(open button)
<button type="button" class="open-overlay">OPEN LAYER</button>
(overlay and close button)
<section class="overlay" aria-hidden="true" tabindex="-1">
<div>
<h2>Hello, I'm the overlayer</h2>
...
<button type="button" class="close-overlay">CLOSE LAYER</button>
</div>
</section>
CSS
.noscroll {
overflow: hidden;
}
.overlay {
position: fixed;
overflow-y: scroll;
inset: 0; }
[aria-hidden="true"] { display: none; }
[aria-hidden="false"] { display: block; }
Javascript (vanilla-JS)
var body = document.body,
overlay = document.querySelector('.overlay'),
overlayBtts = document.querySelectorAll('button[class$="overlay"]'),
openingBtt;
[].forEach.call(overlayBtts, function(btt) {
btt.addEventListener('click', function() {
/* Detect the button class name */
var overlayOpen = this.className === 'open-overlay';
/* storing a reference to the opening button */
if (overlayOpen) {
openingBtt = this;
}
/* Toggle the aria-hidden state on the overlay and the
no-scroll class on the body */
overlay.setAttribute('aria-hidden', !overlayOpen);
body.classList.toggle('noscroll', overlayOpen);
/* On some mobile browser when the overlay was previously
opened and scrolled, if you open it again it doesn't
reset its scrollTop property */
overlay.scrollTop = 0;
/* forcing focus for Assistive technologies but note:
- if your modal has just a phrase and a button move the
focus on the button
- if your modal has a long text inside (e.g. a privacy
policy) move the focus on the first heading inside
the modal
- otherwise just focus the modal.
When you close the overlay restore the focus on the
button that opened the modal.
*/
if (overlayOpen) {
overlay.focus();
}
else {
openingBtt.focus();
openingBtt = null;
}
}, false);
});
/* detect Escape key when the overlay is open */
document.body.addEventListener('keyup', (ev) => {
if (ev.key === "Escape" && overlay.getAttribute('aria-hidden') === 'false') {
overlay.setAttribute('aria-hidden', 'true');
body.classList.toggle('noscroll', false);
openingBtt.focus();
openingBtt = null;
}
})
Finally, here's another example in which the overlay opens with a fade-in effect by a CSS transition applied to the opacity property. Also a padding-right is applied to avoid a reflow on the underlying text when the scrollbar disappears.
Codepen Example (fade)
CSS
.noscroll { overflow: hidden; }
#media (min-device-width: 1025px) {
/* not strictly necessary, just an experiment for
this specific example and couldn't be necessary
at all on some browser */
.noscroll {
padding-right: 15px;
}
}
.overlay {
position: fixed;
overflow-y: scroll;
inset: 0;
}
[aria-hidden="true"] {
transition: opacity 1s, z-index 0s 1s;
width: 100vw;
z-index: -1;
opacity: 0;
}
[aria-hidden="false"] {
transition: opacity 1s;
width: 100%;
z-index: 1;
opacity: 1;
}
overscroll-behavior css property allows to override the browser's default overflow scroll behavior when reaching the top/bottom of content.
Just add the following styles to overlay:
.overlay {
overscroll-behavior: contain;
...
}
Codepen demo
Currently works in Chrome, Firefox and IE(caniuse)
For more details check google developers article.
If you want to prevent overscrolling on ios, you can add position fixed to your .noscroll class
body.noscroll{
position:fixed;
overflow:hidden;
}
Most solutions have the problem that they do not retain the scroll position, so I took a look at how Facebook does it. In addition to setting the underlaying content to position: fixed they also set the top dynamically to retain the scroll position:
scrollPosition = window.pageYOffset;
mainEl.style.top = -scrollPosition + 'px';
Then, when you remove the overlay again, you need to reset the scroll position:
window.scrollTo(0, scrollPosition);
I created a little example to demonstrate this solution
let overlayShown = false;
let scrollPosition = 0;
document.querySelector('.toggle').addEventListener('click', function() {
if (!overlayShown) {
showOverlay();
} else {
removeOverlay();
}
overlayShown = !overlayShown;
});
function showOverlay() {
scrollPosition = window.pageYOffset;
const mainEl = document.querySelector('.main-content');
mainEl.style.top = -scrollPosition + 'px';
document.body.classList.add('show-overlay');
}
function removeOverlay() {
document.body.classList.remove('show-overlay');
window.scrollTo(0, scrollPosition);
const mainEl = document.querySelector('.main-content');
mainEl.style.top = 0;
}
.main-content {
background-image: repeating-linear-gradient( lime, blue 103px);
width: 100%;
height: 200vh;
}
.show-overlay .main-content {
position: fixed;
left: 0;
right: 0;
overflow-y: scroll; /* render disabled scroll bar to keep the same width */
/* Suggestion to put: overflow-y: hidden;
Disabled scrolling still makes a mess with its width. Hiding it does the trick. */
}
.overlay {
display: none;
position: fixed;
top: 0;
left: 0;
width: 100%;
height: 100%;
background: rgba(0, 0, 0, 0.3);
overflow: auto;
}
.show-overlay .overlay {
display: block;
}
.overlay-content {
margin: 50px;
background-image: repeating-linear-gradient( grey, grey 20px, black 20px, black 40px);
height: 120vh;
}
.toggle {
position: fixed;
top: 5px;
left: 15px;
padding: 10px;
background: red;
}
/* reset CSS */
body {
margin: 0;
}
<main class="main-content"></main>
<div class="overlay">
<div class="overlay-content"></div>
</div>
<button class="toggle">Overlay</button>
Don't use overflow: hidden; on body. It automatically scrolls everything to the top. There's no need for JavaScript either. Make use of overflow: auto;. This solution even works with mobile Safari:
HTML Structure
<div class="overlay">
<div class="overlay-content"></div>
</div>
<div class="background-content">
lengthy content here
</div>
Styling
.overlay{
position: fixed;
top: 0px;
left: 0px;
right: 0px;
bottom: 0px;
background-color: rgba(0, 0, 0, 0.8);
.overlay-content {
height: 100%;
overflow: scroll;
}
}
.background-content{
height: 100%;
overflow: auto;
}
See the demo here and source code here.
Update:
For people who want keyboard space bar, page up/down to work: you need to focus on the overlay, e.g., clicking on it, or manually JS focusing on it before this part of the div will respond to keyboard. Same with when the overlay is "switched off", since it's just moving the overlay to the side. Otherwise to browser, these are just two normal divs and it wouldn't know why it should focus on any one of them.
It is worth noting that sometimes adding "overflow:hidden" to the body tag doesn't do the job. In those cases, you'll have to add the property to the html tag as well.
html, body {
overflow: hidden;
}
The behaviour you want to prevent is called scroll chaining. To disable it, set
overscroll-behavior: contain;
on your overlay in CSS.
You can easily do this with some "new" css and JQuery.
Initially: body {... overflow:auto;}
With JQuery you can dynamically switch between 'overlay' and 'body'. When on 'body', use
body {
position: static;
overflow: auto;
}
When on 'overlay' use
body {
position: sticky;
overflow: hidden;
}
JQuery for the switch('body'->'overlay'):
$("body").css({"position": "sticky", "overflow": "hidden"});
JQuery for the switch('overlay'->'body'):
$("body").css({"position": "static", "overflow": "auto"});
if anyone is looking for a solution for React function components, you can put this inside the modal component:
useEffect(() => {
document.body.style.overflowY = 'hidden';
return () =>{
document.body.style.overflowY = 'auto';
}
}, [])
Generally speaking, if you want a parent (the body in this case) to prevent it from scrolling when a child (the overlay in this case) scrolls, then make the child a sibling of the parent to prevent the scroll event from bubbling up to the parent. In case of the parent being the body, this requires an additional wrapping element:
<div id="content">
</div>
<div id="overlay">
</div>
See Scroll particular DIV contents with browser's main scrollbar to see its working.
The chosen answer is correct, but has some limitations:
Super hard "flings" with your finger will still scroll <body> in the background
Opening the virtual keyboard by tapping an <input> in the modal will direct all future scrolls to <body>
I don't have a fix for the first issue, but wanted to shed some light on the second. Confusingly, Bootstrap used to have the keyboard issue documented, but they claimed it was fixed, citing http://output.jsbin.com/cacido/quiet as an example of the fix.
Indeed, that example works fine on iOS with my tests. However, upgrading it to the latest Bootstrap (v4) breaks it.
In an attempt to figure out what the difference between them was, I reduced a test case to no longer depend on Bootstrap, http://codepen.io/WestonThayer/pen/bgZxBG.
The deciding factors are bizarre. Avoiding the keyboard issue seems to require that background-color is not set on the root <div> containing the modal and the modal's content must be nested in another <div>, which can have background-color set.
To test it, uncomment the below line in the Codepen example:
.modal {
position: fixed;
top: 0;
right: 0;
bottom: 0;
left: 0;
z-index: 2;
display: none;
overflow: hidden;
-webkit-overflow-scrolling: touch;
/* UNCOMMENT TO BREAK */
/* background-color: white; */
}
For touch devices, try adding a 1px wide, 101vh min-height transparent div in the wrapper of the overlay. Then add -webkit-overflow-scrolling:touch; overflow-y: auto; to the wrapper. This tricks mobile safari into thinking the overlay is scrollable, thus intercepting the touch event from the body.
Here's a sample page. Open on mobile safari: http://www.originalfunction.com/overlay.html
https://gist.github.com/YarGnawh/90e0647f21b5fa78d2f678909673507f
I found this question trying to solve issue I had with my page on Ipad and Iphone - body was scrolling when I was displaying fixed div as popup with image.
Some answers are good, however none of them solved my issue. I found following blog post by Christoffer Pettersson. Solution presented there helped issue I had with iOS devices and it helped my scrolling background problem.
Six things I learnt about iOS Safari's rubber band scrolling
As it was suggested I include major points of the blog post in case link gets outdated.
"In order to disable that the user can scroll the background page while the "menu is open", it is possible to control what elements should be allowed to be scrolled or not, by applying some JavaScript and a CSS class.
Based on this Stackoverflow answer you can control that elements with the disable-scrolling should not
perform their default scroll action when the touchmove event is triggered."
document.ontouchmove = function ( event ) {
var isTouchMoveAllowed = true, target = event.target;
while ( target !== null ) {
if ( target.classList && target.classList.contains( 'disable-scrolling' ) ) {
isTouchMoveAllowed = false;
break;
}
target = target.parentNode;
}
if ( !isTouchMoveAllowed ) {
event.preventDefault();
}
};
And then put the disable-scrolling class on the page div:
<div class="page disable-scrolling">
Simple inline styling for the body tag:
<body style="position: sticky; overflow: hidden;">
If the intent is to disable on mobile/ touch devices then the most straightforward way to do it is using touch-action: none;.
Example:
const app = document.getElementById('app');
const overlay = document.getElementById('overlay');
let body = '';
for (let index = 0; index < 500; index++) {
body += index + '<br />';
}
app.innerHTML = body;
app.scrollTop = 200;
overlay.innerHTML = body;
* {
margin: 0;
padding: 0;
}
html,
body {
height: 100%;
}
#app {
background: #f00;
position: absolute;
height: 100%;
width: 100%;
overflow-y: scroll;
line-height: 20px;
}
#overlay {
background: rgba(0,0,0,.5);
position: fixed;
top: 0;
left: 0;
right: 0;
height: 100%;
padding: 0 0 0 100px;
overflow: scroll;
}
<div id='app'></div>
<div id='overlay'></div>
(The example does not work in the context of Stack Overflow. You will need to recreate it in a stand-alone page.)
If you want to disable scrolling of the #app container, just add touch-action: none;.
I'd like to add to previous answers because I tried to do that, and some layout broke as soon as I switched the body to position:fixed. In order to avoid that, I had to also set body's height to 100% :
function onMouseOverOverlay(over){
document.getElementsByTagName("body")[0].style.overflowY = (over?"hidden":"scroll");
document.getElementsByTagName("html")[0].style.position = (over?"fixed":"static");
document.getElementsByTagName("html")[0].style.height = (over?"100%":"auto");
}
Use the following HTML:
<body>
<div class="page">Page content here</div>
<div class="overlay"></div>
</body>
Then JavaScript to intercept and stop scrolling:
$(".page").on("touchmove", function(event) {
event.preventDefault()
});
Then to get things back to normal:
$(".page").off("touchmove");
In my case, none of these solutions worked out on iPhone (iOS 11.0).
The only effective fix that is working on all my devices is this one - ios-10-safari-prevent-scrolling-behind-a-fixed-overlay-and-maintain-scroll-position
try this
var mywindow = $('body'), navbarCollap = $('.navbar-collapse');
navbarCollap.on('show.bs.collapse', function(x) {
mywindow.css({visibility: 'hidden'});
$('body').attr("scroll","no").attr("style", "overflow: hidden");
});
navbarCollap.on('hide.bs.collapse', function(x) {
mywindow.css({visibility: 'visible'});
$('body').attr("scroll","yes").attr("style", "");
});
One solution for a React functional component is to use the useEffect hook.
Here's the code example bellow (pay attention to the useEffect definition):
import {useEffect, useRef} from "react";
export default function PopoverMenu({className, handleClose, children}) {
const selfRef = useRef(undefined);
useEffect(() => {
const isPopoverOpenned = selfRef.current?.style.display !== "none";
const focusedElement = document?.activeElement;
const scrollPosition = {x: window.scrollX, y: window.scrollY};
if (isPopoverOpenned) {
preventDocBodyScrolling();
} else {
restoreDocBodyScrolling();
}
function preventDocBodyScrolling() {
const width = document.body.clientWidth;
const hasVerticalScrollBar = (window.innerWidth > document.documentElement.clientWidth);
document.body.style.overflowX = "hidden";
document.body.style.overflowY = hasVerticalScrollBar ? "scroll" : "";
document.body.style.width = `${width}px`;
document.body.style.position = "fixed";
}
function restoreDocBodyScrolling() {
document.body.style.overflowX = "";
document.body.style.overflowY = "";
document.body.style.width = "";
document.body.style.position = "";
focusedElement?.focus();
window.scrollTo(scrollPosition.x, scrollPosition.y);
}
return () => {
restoreDocBodyScrolling(); // cleanup on unmount
};
}, []);
return (
<>
<div
className="backdrop"
onClick={() => handleClose && handleClose()}
/>
<div
className={`pop-over-menu${className ? (` ${className}`) : ""}`}
ref={selfRef}
>
<button
className="pop-over-menu--close-button" type="button"
onClick={() => handleClose && handleClose()}
>
X
</button>
{children}
</div>
</>
);
}
Originally posted on this other related Stackoverflow question: https://stackoverflow.com/a/69016517/14131330
CSS
.noScroll {
overflow: hidden;
}
Javascript
<script>
function toggleNav() {
document.body.classList.toggle("noScroll");
}
</script>
Button
<button onclick="toggleNav()">
Toggle Nav
</button>
If you want to stop body/html scroll add as the following
CSS
html, body {
height: 100%;
}
.overlay{
position: fixed;
top: 0px;
left: 0px;
right: 0px;
bottom: 0px;
background-color: rgba(0, 0, 0, 0.8);
.overlay-content {
height: 100%;
overflow: scroll;
}
}
.background-content{
height: 100%;
overflow: auto;
}
HTML
<div class="overlay">
<div class="overlay-content"></div>
</div>
<div class="background-content">
lengthy content here
</div>
Basically, you could do it without JS.
The main idea is to add html/body with height: 100% and overflow: auto.
and inside your overlay, you could either enable/disable scroll based on your requirement.
Hope this helps!
Use below code for disabling and enabling scroll bar.
Scroll = (
function(){
var x,y;
function hndlr(){
window.scrollTo(x,y);
//return;
}
return {
disable : function(x1,y1){
x = x1;
y = y1;
if(window.addEventListener){
window.addEventListener("scroll",hndlr);
}
else{
window.attachEvent("onscroll", hndlr);
}
},
enable: function(){
if(window.removeEventListener){
window.removeEventListener("scroll",hndlr);
}
else{
window.detachEvent("onscroll", hndlr);
}
}
}
})();
//for disabled scroll bar.
Scroll.disable(0,document.body.scrollTop);
//for enabled scroll bar.
Scroll.enable();