Replace mechanism for creating customized built-in elements

page/skooma.html

@@ -139,15 +139,6 @@
 			return div
 		</code-block>
 
-		<p>Custom elements with hyphenated names can be created easily</p>
-		<p></p>
-		<code-block>
-			return html.myComponent()
-		</code-block>
-		<code-block>
-			return document.createElement("my-component")
-		</code-block>
-
 		<p>
 			Function arguments will be called on the new element.<br>
 			This can be used to easily add custom initialisation logic to elements.
@@ -163,6 +154,27 @@
 			element.innerText += ", world!"
 			return element
 		</code-block>
+
+		<p>Custom elements with hyphenated names can be created easily</p>
+		<p></p>
+		<code-block>
+			return html.myComponent()
+		</code-block>
+		<code-block>
+			return document.createElement("my-component")
+		</code-block>
+
+		<p>Custom built-ins can be created with the <code>is</code> attribute.</p>
+		<p></p>
+		<code-block>
+			return html.span({is: "my-span"})
+			// Also sets the `is` attribute, useful for selectors
+			// like span[is="my-span"]
+		</code-block>
+		<code-block>
+			return document.createElement("span", {is: "my-span"})
+			// No actual `is` attribute. GL styling these.
+		</code-block>
 	</div>
 </section>
 

skooma.js

@@ -31,6 +31,19 @@ const parseAttribute = (attribute) => {
 		return JSON.stringify(attribute)
 }
 
+
+const defined = (value, fallback) => typeof value != "undefined" ? value : fallback
+const getCustom = args => String(
+	args.reduce(
+		(current, argument) => Array.isArray(argument)
+			? defined(getCustom(argument), current)
+			: (argument && typeof argument == "object")
+			? defined(argument.is, current)
+			: current
+		,null
+	)
+)
+
 const parseArgs = (element, before, ...args) => {
 	if (element.content) element = element.content
 	for (let arg of args) if (arg !== empty)
@@ -64,11 +77,9 @@ const parseArgs = (element, before, ...args) => {
 }
 
 const nop = object => object
-const node = (_name, args, options) => {
+const node = (name, args, options) => {
 	let element
-	const [name, custom] = _name
+	let custom = getCustom(args)
-		.match(/[^$]+/g)
-		.map(options.nameFilter ?? nop)
 	if (options.xmlns)
 		element = document.createElementNS(options.xmlns, name, {is: custom})
 	else