March 09, 2024

Fast Smooth Scroll Plugin

This lightweight plugin enhances user experience by enabling smooth scrolling for anchor links without the need for jQuery or other dependencies.

This plugin takes a no-frills approach to smooth scrolling, providing a fast, performant, and accessible user experience.

Simply enable the plugin, and any anchor links (i.e. links that point to other content on the same page) will provide a smooth scrolling experience rather than abruptly jumping to the destination content.

The plugin relies on the latest smooth scrolling techniques using CSS. A very fast and lightweight JavaScript polyfill (<1KB) is included to equally support older browsers, including Internet Explorer. So you can rest assured this plugin covers your userbase.

Why does this plugin exist?

Smooth scrolling is a basic feature to enhance user experience, so it shouldn’t come at a performance cost that at the same time harms user experience elsewhere.

Several other smooth scrolling solutions unfortunately rely on outdated techniques such as jQuery, which can hurt your site’s performance, and is really not necessary to provide the feature. Even browsers as old as 10 years don’t need jQuery to achieve smooth scrolling. In fact, as of today you can achieve the behavior with only CSS, not even requiring any JavaScript.

Another potential reason to use this plugin over other smooth scrolling solutions is accessibility: This plugin respects the user preferences around reduced motion, which can avoid discomfort for those with vestibular motion disorders.

You may already use a smooth scrolling plugin, but it is worth double checking that it doesn’t use one of those outdated, inefficient, and inaccessible approaches that may slow down your site or affect user interactions negatively.

More technical details

This plugin simply enables smooth scrolling with the scroll-behavior CSS property. This property has been supported by all modern browsers for a few years now.

To support older browsers as well, a lightweight JavaScript polyfill is included, which is only loaded for browsers that lack support for the CSS property and doesn’t require any dependencies. The polyfill uses latest JavaScript user experience best practices such as requestAnimationFrame to provide a smooth scrolling experience without potentially blocking other user interactions.

For relevant browser support, see:
* CSS Scroll-behavior
* CSS property: scroll-padding-top
* prefers-reduced-motion media query
* requestAnimationFrame
* High Resolution Time API
* NodeList API
* Window API: scrollTo

Installation

Upload the entire fast-smooth-scroll folder to the /wp-content/plugins/ directory or download it through the WordPress backend.
Activate the plugin through the ‘Plugins’ menu in WordPress.

FAQ

Where can I configure the plugin?

This plugin doesn’t come with a settings screen or options of any kind. You install it, and it just works.

Why is the scrolling slightly off vertically?

If the anchor scrolling doesn’t end up in exactly the right place, there is a good chance this is happening because your site uses a fixed header or another element that overlaps the main content.

For such situations, the plugin supports setting a scroll offset. You can use the filter fast_smooth_scroll_offset to set such an offset in pixels (default is 0, i.e. no offset).

For example, with the following code you would set a scroll offset of 120 pixels. This works for both the default CSS-only implementation as well as for the JavaScript polyfill.

<?php function myplugin_get_custom_scroll_offset() { return 120; } add_filter( 'fast_smooth_scroll_offset', 'myplugin_get_custom_scroll_offset' );

Does the plugin support reduced motion preferences?

Yes! For better accessibility, clients that are configured to reduce motion will not be affected by the smooth scroll behavior.

The prefers-reduced-motion media query is used to detect such a preference. Note that this only works with the CSS-only solution, as the older browsers that would require the JavaScript polyfill do not support this preference.

I don’t care about smooth scrolling for older browsers. How can I disable the JavaScript polyfill?

Since the JavaScript polyfill is only loaded when needed and is extremely lightweight, there’s probably not much value in disabling it. However, if you want to go for the purist solution of only relying on the CSS approach, you can certainly do so, using the built-in filter fast_smooth_scroll_enqueue_scripts, which defaults to true.

For example, with the following code you would ensure the JavaScript polyfill and even the simple feature detection check are never loaded:

<?php add_filter( 'fast_smooth_scroll_enqueue_scripts', '__return_false' );

How can I test the JavaScript polyfill?

Most likely, you are using a modern browser which therefore does not trigger the JavaScript polyfill to load.

If you don’t have a legacy browser handy, you can still test the behavior: You’ll need to be logged in as an administrator, and then you can add a query parameter fast_smooth_scroll_debug_polyfill=1 to any URL. For example, in case of the home page:

https://my-site.com/?fast_smooth_scroll_debug_polyfill=1

Where should I submit my support request?

For regular support requests, please use the wordpress.org support forums. If you have a technical issue with the plugin where you already have more insight on how to fix it, you can also open an issue on GitHub instead.

How can I contribute to the plugin?

If you have ideas to improve the plugin or to solve a bug, feel free to raise an issue or submit a pull request in the GitHub repository for the plugin. Please stick to the contributing guidelines.

You can also contribute to the plugin by translating it. Simply visit translate.wordpress.org to get started.

Changelog

1.0.0

First stable version

1.0.0-beta.2

Enhanced: Introduce support for optional scroll offset via new filter fast_smooth_scroll_offset. Props erikyo.
Fixed: Support prefers-reduced-motion and disable smooth scrolling if reduced motion is preferred. Props queerdevperson.
Fixed: Avoid unnecessarily set scroll-behavior style property on the html element.

1.0.0-beta.1

First beta release