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GitHub package document.defineElement is a polyfill for document.registerElement that does not require a hypen in the nodename. This enables you to register <thing></thing> in stead of <x-thing></x-thing>.
Of course it doesn't have to be used as a polyfill, you could stick it in your Electron application or whatever.
What is this?
The DOM's document.registerElement requires you to include a hyphen in the node name to prevent conflict. I refused to accept this rule and this is the result.
- document.defineElement is a polyfill for document.registerElement modified to allow elements without a hyphen (-)
- document.defineElement works even in browsers that do not implement document.registerElement.
- document.defineElement is renamed to prevent conflict with document.registerElement.
- document.defineElement lets you overwrite all existing DOM node behaviors.
- document.defineElement can be used to create dynamic and interactive HTML node types.
document.defineElement()
Just like document.registerElement, your new class supports the following (optional) callbacks. The following method/syntax is identical to using registerElement and should be pretty straightforward.
class HTMLSomeCustomElement extends HTMLElement {
/* Fires when an instance of the element is created. */
createdCallback() {
/* */
}
/* Fires when an instance was inserted into the document. */
attachedCallback() {
/* */
}
/* Fires when an instance was removed from the document. */
detachedCallback() {
/* */
}
/* Fires when an attribute was added, removed, or updated. */
attributeChangedCallback(attr, oldVal, newVal) {
/* */
}
}
document.defineElement('custom-element', HTMLSomeCustomElement)
/* now every <custom-element></custom-element> will be an instanceof HTMLSomeCustomElement */
/* or you can do this too */
var Custom = document.defineElement('custom-element', HTMLSomeCustomElement)
document.body.appendChild(new Custom())
/* or simply this works as well */
document.createElement('custom-element')
Simple clock, an actual example
The following custom element will show the current time and update it every second like a clock. In this example we are not using a hyphen in the node name. All we need to show a clock in our custom interface framework thing is put
<clock></clock>
somewhere.
class HTMLSimpleClockElement extends HTMLSpanElement {
createdCallback() {
var self = this
/* we could do something with this.getAttribute() for instance set interval */
this.interval = setInterval(function() {
self.innerText = new Date(new Date().getTime()).toLocaleTimeString()
}, 1000)
}
}
document.registerElement('clock', HTMLSimpleClockElement)
<body>
<clock></clock>
</body>
You could support some attributes on the clock such as the refresh interval or display string template and then check this.attributes in the created or attached callback function.
Ideas
I am not very imaginative. Sorry.
- create an
<include></include>element that fetches remote content and renders it. - design a
<chat></chat>element that automatically connects to your WebSocket server - something with
<user></user>or<like-button></like-button>
Bad ideas
- completely overwrite the
<body>element and break things - make iframes or script tags stop working
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