slide-element
v2.3.1
Published
A tiny, accessible, Promise-based, jQuery-reminiscent library for hiding and showing elements in a sliding fashion.
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slide-element
A tiny, accessible, Promise-based, jQuery-reminiscent library for sliding elements with dynamic heights open & closed.
To see it in action, check out the following demos:
Why?
Using JavaScript to animate an element open and closed hasn't traditionally been a straightforward task, especially if it contains dynamically sized content. You could go with something like jQuery's slideToggle()
, but that path would require you to take on a lot more code than necessary. Another option is using CSS to change the max-height
value of an element, but this approach is filled with arbitrariness and difficult to pull off well when you're not sure how much content you'll be animating over.
This library gets the job done using the Web Animations API, and it doesn't require elements to have fixed heights. Instead, element heights are calculated based on their contents, and then the appropriate values are applied to trigger a smooth, native transition. The animations themselves are powered by the same mechanics used within CSS transitions, making it one of the best ways to pull it off in terms of performance.
It's small, smooth, and focuses on doing one job well: sliding stuff open and closed.
Installation
Run npm install slide-element
, or use a CDN like unpkg.
Setup
Make sure your target element is set to display: none;
.
Usage
Toggling Elements
Use the toggle
function to slide an element open & closed based on its current state.
import { toggle } from "slide-element";
document.getElementById("button").addEventListener("click", (e) => {
toggle(document.getElementById("box"));
});
Sliding Elements Down
Use the down
function to slide an element open.
import { down } from "slide-element";
document.getElementById("button").addEventListener("click", (e) => {
down(document.getElementById("boxToSlideOpen"));
});
Sliding Elements Up
Use the up
function to slide an element closed, and then set its display
property to none
.
import { up } from "slide-element";
document.getElementById("button").addEventListener("click", (e) => {
up(document.getElementById("boxToSlideClosed"));
});
Everything's a Promise
Each of the functions provided return promises, so you can easily wait to perform an action after an animation is complete. The resolved value will indicate if the element has just been opened (true
), closed (false
), or the result of an animation that interruped another (see more below).
import { toggle } from "slide-element";
document.getElementById("button").addEventListener("click", (e) => {
toggle(document.getElementById("someElement")).then((isOpen: boolean | null) => {
console.log("Toggling is done!");
});
});
Interrupting In-Progress Animations
Depending on your settings, some users may be able to repeatedly trigger a new before a previous one has been allowed to finish, which will cause the in-progress animation instantly finish before the new one can begin.
When this occurs, the isOpen
Promise that resolves after the animation is complete will return null
for each animation that was triggered in interruption of the first. The initial animation, however will still resolve to the correct value. For example, pretend the following animation is clicked rapidly three times in a row.
import { toggle } from "slide-element";
document.getElementById("button").addEventListener("click", (e) => {
toggle(document.getElementById("someElement")).then((isOpen: boolean | null) => {
console.log(isOpen);
});
});
When the animation has been allowed to complete, the following values will be logged -- two null
values for the interrupting animations, and one boolean for the initial (and now complete) one. The point here is that it may be necessary to explicitly check for a non-null
value when using the resolved "open" state.
true
null
null
Animating Boxes with Padding
If the element you're animating has any padding
set to it, be sure to also apply box-sizing: border-box
as well. If you don't, the resulting animation will be weird and jumpy.
<div id="myTarget" style="padding: 1rem; box-sizing: border-box; display: none;">
My contents!
</div>
Customizing the Animation
By default, slide-element
uses the following transition property values:
Property | Value
-------------------------------------------------------------------------------------------------------- | ------
duration (in milliseconds) | 250
easing (choose one) | ease
You can override these by passing an object as the seceond parameter of any method:
up(document.getElementById("element"), {
duration: 500,
easing: "ease-in-out",
});
Customizing the Opened display
Value
Out of the box, slide-element
will set your opened element to display: block;
. If you'd like to customize this, pass a display
value as an option:
down(document.getElementById("element"), {
display: "flex"
});
Customizing the overflow
Value Used During Animation
Out of the box, slide-element
will animate your element open & closed with overflow: hidden;
. If you'd like to pass your own value, use the overflow
option:
down(document.getElementById("element"), {
overflow: "auto"
});
Usage w/o a Bundler
If you'd like to use slide-element
directly in the browser via CDN, simply load the code, and then reference the function you'd like to use on the global SlideElement
object:
<script src="./path/to/slide-element.js"></script>
<script>
document.getElementById('someElement').addEventListener('click', (e) => {
SlideElement.toggle(document.getElementById("someBox"));
});
</script>
API
// Toggle an element based on current state.
toggle(element: HTMLElement, options?: object): Promise<boolean>
// Slide an element down.
up(element: HTMLElement, options?: object): Promise<boolean>
// Slide an element down.
down(element: HTMLElement, options?: object): Promise<boolean>
Param | Type | Description
------- | ------------- | --------------------------------------------
element | HTMLElement
| A single HTML node to be slid open or closed
options | object
| Options to customize sliding animation.
Accessibility
This library will respect the prefers-reduced-motion
setting on a user's machine. When it's set to reduce
, the sliding animation will be forced to a duration of 0
, making the respective elements open and close instantly.
Additionally, it's highly recommended that you toggle the aria-expanded
attribute on any element (like a button) that's responsible for triggering an animation. This can be done by adding a single line of code that fires afters an animation is complete:
document.getElementById('someButton').addEventListener('click', (e) => {
toggle(document.getElementById('thing2')).then((opened) => {
<!-- Set the appropriate `aria-expanded` value based on the state of the container. -->
e.target.setAttribute("aria-expanded", opened);
});
});
Show Off Your Use Case
I love to see examples of how you're using the stuff I build. If you're comfortable, please send it my way!