The scroll-behavior property in CSS allows us to define whether the scroll location of the browser jumps to a new location or animates the transition when a user clicks a link that targets an anchored position within a scrolling box.
Smooth scrolling (the animated change of position within the viewport from the originating link to the destination anchor) can be a nice interaction detail added to a site, giving a polished feel to the experience. If you don't believe me, look at how many people have responded to the Smooth Scrolling snippet here on CSS-Tricks.
The overflow-anchor property enables us to opt out of Scroll Anchoring, which is a browser feature intended to allow content to load above the user's current DOM location without changing the user's location once that content has been fully loaded.
Scrolling is complicated. Nolan Lawson:
- User scrolls with two fingers on a touch pad
- User scrolls with one finger on a touch screen
- User scrolls with a mouse wheel on a physical mouse
- User clicks the sidebar and drags it up and down
- User presses up, down, PageUp, PageDown, or spacebar keys on a keyboard
As it turns out, all five of these input methods have vastly different characteristics, especially when it comes to performance and cross-browser behavior. Some of them (such as touch screen scrolling) are likely to be smooth even on a page with heavy JavaScript usage, whereas others (such as keyboard scrolling) will make the same page feel laggy and unresponsive. Furthermore, some kinds of scrolling can be slowed down by DOM event handlers, whereas others won't.
The web is a rather vertical place. You read a web site like you read a physical page: left to right, top to bottom. But sometimes, you want to step away from the verticality of it all and do something crazy: make a horizontal list. Or even crazier, a horizontal site!
The following is a guest post by Micah Miller-Eshleman. Micah designed a variation of the "Priority+ Navigation" concept and uses it in production at the college he works for. I always dig a show & tell behind the thinking and creation of a design pattern, especially when it's working out there in the real world.
The following is a guest post by Michał Sajnóg, a front end developer at Netguru. Michał has created one of those "when you scroll to here, trigger this animation" libraries. One of the things I like about it is that it leaves as much as it can to CSS for creating and controlling the animation themselves. Not to mention it's proved itself by working well on a number of production sites. I'll let Michał walk you through it.
Native browser smooth scrolling is like this:
// 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'
});Dustan Kasten has a polyfill for this.
Whatever technology you use for smooth scrolling, accessibility is a concern. For example, if you click a #hash link, the native behavior is for the browser to change focus to the element matching that ID. The page may scroll, but the scrolling is a side effect of the focus changing.
If you override the default focus-changing behavior (which you have to, to prevent instant scrolling and enable smooth scrolling), you need to handle the focus-changing yourself.
Heather Migliorisi wrote about this, with code solutions, in Smooth Scrolling and Accessibility.
jQuery can also do this. Here's the code to perform a smooth page scroll to an anchor on the same page. It has some logic built in to identify those jump links, and not target other links.
// Select all links with hashes
$('a[href*="#"]')
// Remove links that don't actually link to anything
.not('[href="#"]')
.not('[href="#0"]')
.click(function(event) {
// On-page links
if (
location.pathname.replace(/^\//, '') == this.pathname.replace(/^\//, '')
&&
location.hostname == this.hostname
) {
// Figure out element to scroll to
var target = $(this.hash);
target = target.length ? target : $('[name=' + this.hash.slice(1) + ']');
// Does a scroll target exist?
if (target.length) {
// Only prevent default if animation is actually gonna happen
event.preventDefault();
$('html, body').animate({
scrollTop: target.offset().top
}, 1000, function() {
// Callback after animation
// Must change focus!
var $target = $(target);
$target.focus();
if ($target.is(":focus")) { // Checking if the target was focused
return false;
} else {
$target.attr('tabindex','-1'); // Adding tabindex for elements not focusable
$target.focus(); // Set focus again
};
});
}
}
});See the Pen Smooth Page Scrolling in jQuery by Chris Coyier (@chriscoyier) on CodePen.