@sirpepe/animated-highlight
v1.0.1
Published
The element `<animated-highlight>` does precisely one thing: it [slots](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/slot) another element and switches classes on it. Its use case is to serve as a sort of runtime for code generated by [diff2g
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<animated-highlight>
The element <animated-highlight>
does precisely one thing: it slots another element and switches
classes on it. Its use case is to serve as a sort of runtime for code generated
by diff2gif.com. The element is extremely basic and
meant to be hacked and extended by you, the user.
HTML API
General usage
The element <animated-highlight>
is a custom element with several slots,
attributes, and DOM properties for customization. To get it working, just
include dist/bundle.js
in a script tag in your web page! A minimal example:
<script src="dist/bundle.js"></script>
<animated-highlight controls keyframes="0 1 2 3">
<div>Switch classes on me!</div>
</animated-highlight>
This will cycle classes on the div
element wrapped by the custom elements from
frame0
to frame1
to frame2
to frame3
. The keyframes are defined as a
whitespace-separated list of numbers in the keyframes
attribute while the
existence of the controls
attribute provides basic forwards/backwards buttons.
Attribute summary:
controls
: When present, shows controls UI (by default just a pair of forwards/backwards buttons). Reflected by the DOM propertycontrols
keyframes
: Defines the list of keyframes with a value of whitespace-separated positive integers. Values that are anything but a list of whitespace-separated numbers are equal to the attribute missing (eg. there are no keyframes at all in this case). The list of keyframes is always sorted in ascending order and cleared of any duplicates or non-numbers. Negative numbers are interpreted as positive numbers.current
: Indicates the current frame. Can be changed to change the current frame. Reflected by the DOM propertycurrent
. Values that are anything but a positive integer are treated as0
.
Custom controls
The default control UI for the element is basic and ugly. There are three options to remedy this:
1. Wrap the element
You can simply wrap an <animated-highlight>
element without a controls
attribute and add your own custom logic that uses the JavaScript API described
below. This is probably the way to go for integration in Frameworks like React.
2. Style the controls
If you just want to reposition and re-style the existing controls, you can use
the following CSS ::part()
selectors:
animated-highlight::part(controls)
: The container element for the buttonsanimated-highlight::part(controls-prevBtn)
: The "previous" buttonsanimated-highlight::part(controls-nextBtn)
: The "next" buttons
The buttons are <button>
elements with <span>
element inside.
3. Replace the controls
The default controls are actually just fallback content for a shadow DOM slot. This means that you can very easily just add your own:
<animated-highlight controls keyframes="0 1 2 3">
<div>Switch classes on me!</div>
<div slot="controls">
<div data-command="prev">Back</div>
<div data-command="next">Next</div>
</div>
</animated-hightlight>
All you need to do to make your custom buttons (in this case, <div>
elements)
work is add the attributes <div data-command="prev">Back</div>
and
<div data-command="next">Next</div>
respectively. You can also build up your
custom controls to do way more than just provide two buttons. See
demo/index.html
for an example.
4. Hack the element
The element's shadow root is open and most of the private properties on the
AnimatedHighlight
class are actually private. Go and mess with 'em!
JavaScript API
This package provides an ECMAScript module that exports the class for the custom element. To get it working, import the class from the module and register it as a new element:
import { AnimatedHighlight } from "animated-highlight";
window.customElements.get("animated-highlight") ??
window.customElements.define("animated-highlight", AnimatedHighlight);
getter/setter controls
(boolean)
Reflects the HTML attribute controls
. Setting this property to a falsy value
removes the attribute.
getter/setter current
(number)
Reflects the current keyframe. The setter coerces and rounds values to whole numbers and clamps them to the range of available keyframes.
getter nextCurrent
(number | null)
Reflects the keyframe the element is about to switch to during an
ah-beforeframechange
event. This property is only set to a number during this
event and returns null
at any other time.
getter maxFrame
(number)
Returns the last keyframe.
getter/setter keyframes
(Array)
Reflects the HTML attribute keyframes
. Setting this property to anything but
an array is equal to setting the property to an empty array.
methods next()
and prev()
Go to the next or previous keyframe respectively, unless the corresponding
beforeframechange
event gets cancelled. Returns a number indicating the
new keyframe.
Event ah-beforeframechange
(bubbles, cancelable, not composed)
Fires before a frame change occurs. Call preventDefault()
on the event to stop
the frame change from happening. You can inspect the event target's current
property to figure out the current frame and the event target's nextCurrent
property to see what the next frame is going to be... and then decide whether or
not you want to to stop the frame change.
Event ah-afterframechange
(bubbles, not cancelable, not composed)
As the name suggests, this is fired after a frame change has occurred.
Notes
Neither dom properties nor HTML attributes for the events ah-beforeframechange
and ah-afterframechange
are implemented! You must use addEventListener()
,
attributes or properties like onAhAfterframechange = ...
are not supported.
Integrations
TypeScript
The module provides types for the element's class AnimatedHighlight
and adds
its declarations into HTMLElementTagNameMap
. This ensures that built-ins like
document.createElement()
know how to handle the new tag name
animated-highlight
. Unless you want to use another tag name or integrate with
special HTML snowflakes like react, you don't have to do anything.