Improve documentation of render function

doc/readme.md

@@ -0,0 +1,93 @@
+## Skooma.js
+
+### HTML Proxy
+
+The proxy object that does the actual HTML generation.
+
+```js
+document.body.append(html.div(
+   html.span("Hello, World!")
+))
+```
+
+### Handle helper
+
+Wraps a funcion of the signature `event, ... -> value` so that
+`event.preventDefault` gets called before running the function.
+
+```js
+button.addEventListener("click",
+   handle(() => console.log("click"))
+)
+```
+
+### Fragment helper
+
+Wraps a list of elements in a new document fragment.
+
+```js
+const spans = fragment(
+   html.span("First span"),
+   html.span("Second span")
+)
+document.body.append(spans.cloneNode())
+```
+
+### Text helper
+
+When called as a normal function, returns a new text node with the given
+content. Unlike `document.createTextNode`, it does not fail for non-string
+values.
+
+```js
+const node = text("Hello, World!")
+```
+
+When used as a tagged template, returns a document fragment containing text
+nodes and interpolated values. DOM nodes can be interpolated into the document
+fragment.
+
+```js
+const description = text`Interpolate ${html.b("bold")} text`
+```
+
+For consistency, even tagged templates with no interpolated variables will
+always return a document fragment.
+
+## State.js
+
+### AbortRegistry
+
+`FinalizationRegistry` that takes an `AbortController` and aborts it whenever
+the registered value gets collected.
+
+### ChangeEvent
+
+The event class emitted when a change is detected on a skooma state.
+Provides the `final` getter.
+
+### MapStorage
+
+A utility class that simulates the `Storage` API but is backed by a map. Can be
+used as fallback in environments where persistent storages aren't available.
+
+### SimpleState
+
+Base state class that all other states inherit from, used primarily for class
+checking, as the `State` class introduces behaviours that may be undesireable
+when inheriting.
+
+### State
+
+The main state class that does all the magic.
+
+### ForwardState
+
+Proxy to a named property on another State to be used with APIs that only accept
+single-value states.
+
+### StoredState
+
+State class that is backed by a Storage instead of an internal proxy.
+
+## domLense.js

doc/render.md

@@ -0,0 +1,174 @@
+# Rendering DOM nodes using `render.js`
+
+```js
+import {html} from "skooma/render.js"
+```
+
+A functional-friendly helper library for procedural DOM generation and templating, with support for reactive state objects.
+
+## Summary
+
+```js
+html.button(
+	"Clicki Me!",
+	{
+		class: "primary",
+		click({target}) {
+			console.log("User clicked", target)
+		}
+	},
+	button => { console.log("Created", button) }
+)
+```
+
+* elements as functions `content -> element`
+* content as arguments or in arrays
+* attributes in object arguments
+* style, dataset, shadow root, etc. as magic attributes
+* events as function attributes
+* initialisers as `void -> void` functions
+
+## Interface / Examples
+
+### Basic DOM generation
+
+Accessing the `html` proxy with any string key returns a new node generator function.
+When called this function will generate a DOM node (HTML Tag).
+The name of the function becomes the tag name of the node.
+
+```js
+html.div()
+```
+
+Content and attributes can be set via the function arguments:
+Strings and DOM nodes are inserted as children, while other objects (except for some special cases) have their key-value pairs turned into attribute-value pairs on the 
+
+```js
+html.div("Big Text", {style: "font-size: 1.4em"})
+```
+
+Arrays are iterated and their values treated as arguments.
+This works both for inserting children and setting attributes.
+
+```js
+const content = [" ps: hi", {class: "title"}]
+html.h1({id: "main-heading"}, "Heading", content)
+```
+
+Function arguments are treated differently depending on their length:]
+Functions with **no** named parameters are called, and their return value is then evaluated just like an argument to the generator.
+
+All other functions are (immediately) called with the newly created node as their first and only argument.
+These can be used to initialise the new node in a point-free style.
+
+```js
+const hello = () => html.bold("Hello, World!")
+const init = node => console.log("Initialising", node)
+html.div(hello, init)
+```
+
+Nested tags can be generated with nested function calls.
+When properly formatted, this means simpler templates will have the same structure as if written in HTML (sans those pesky closing tags).
+
+```js
+html.div(
+    html.p(
+        html.b("Bold Text")
+    )
+)
+```
+
+### Attribute Processing
+
+For convenience, arrays assigned as attributes will be joined with spaces:
+
+```js
+html.a({class: ["button", "important"]})
+```
+
+Assigning a function as an attribute will instead attach it as an event listener:
+
+```js
+html.button("Click me!", {click: event => {
+    alert("You clicked the button.")
+}})
+```
+
+The special `style` property can be set to an object and its key/value pairs will be inserted as CSS properties on the element's `style` object.
+
+```js
+const style = { color: "salmon" }
+html.span("Salmon", { style })
+```
+
+The special property `shadowRoot` will attach a shadow-DOM to the element if none is present and append its content to the shadow root.
+Arrays are iterated over and their elements appended individually.
+
+```js
+html.div({
+   shadowRoot = ["Hello, ", html.b("World"), "!"]
+})
+```
+
+The `dataset` property will add its key/value pairs to the new node's `dataset`,
+as a more convenient alternative to setting individual `data-` attributes.
+
+```js
+const dataset = { foo: "bar" }
+const div = html.div({dataset})
+console.log(dataset.foo === div.dataset.foo)
+console.log(div.getAttribute("data-foo") === "bar")
+```
+
+### Reactivity
+
+Skooma supports reactivity through a simple protocol:
+
+Observable objects identify themselves with the `observable` attribute,
+which must return a truthy value.
+
+Observables are expected to expose a `value` attribute that is both readable and writeable,
+and to emit a "change" event whenever its vale has changed.
+
+Observables can be passed to skooma's node functions as both
+attribute values (values in an object) or
+child elements (direct arguments or in an array).
+
+#### Reactive Children
+
+Passing an observable as a child element will attempt to insert its current
+value into the new node as if it was passed in directly, but will also hook into
+the observable to replace the value when the state changes.
+
+```js
+const state = new Observable.value(0)
+
+const button = html.button(state, {
+	click(event) { state.value++ }
+})
+```
+
+Note that to keep the replacement logic simple, it is not currently possible to
+insert use document fragments, as these could insert several top-level children
+into a component that would then all have to be replaced. When an observable
+contains or changes to a document fragment, skooma will raise an error.
+
+Before replacing an element, a `"replace"` event is emitted from the old
+element. This event bubbles and is cancelable, and can thus be used both to
+completely prevent the replacement according to custom logic, to alter or
+initialise the new element before it is inserted, or even to modify the old
+object instead of replacing it.
+
+#### Reactive Attributes
+
+Passing an observable as an object value will, likewise, treat its value as the
+attribute value, and update it whenever the state's value changes.
+
+```js
+const state = new Observable.value(0)
+
+const input_1 = html.input({ type: "number", value: state })
+const input_2 = html.input({ type: "number", value: state })
+```
+
+TODO: events as for reactive children

readme.md

@@ -1,12 +1,40 @@
 # Skooma
 
-A functional-friendly helper library for procedural DOM generation and
-templating.
-
 ```js
-import {html} from "skooma.js"
+import {html} from "skooma/render.js"
+
+document.body.append(
+	html.p(
+		"This is a paragraph with some text ",
+		html.b("and some bold text "),
+		html.img({
+			alt: "And an image",
+			href: "http://picsum.photos/200/200"
+		})
+	)
+)
 ```
 
+## Goals
+
+1. `skooma/render` should stay small enough to use it as just a helper library
+   to generate some dom nodes in any sort of web environment.
+1. `skooma/observable` should likewise function as a standalone reactive state
+   management library to be used with or without a framework
+1. A developer who doesn't use skooma should be able to read any code using it
+   and piece together what it does based on structure and function names
+1. Skooma should be easy to gradually introduce into an application that uses
+   a different framework or no framework at all
+1. Skooma should make it easy to gradually replace it with a different solution
+   should it prove unfit for a project it is being used in
+1. The library should be hackable so that developers can tweak it for different
+   environments like SSR or frameworks
+
+## Warning
+
+**This branch is in the process of being aggressively refactored and improved.
+This readme file may not reflect the latest state of the interface.**
+
 ## Overview
 
 ```js
@@ -22,7 +50,7 @@ document.body.append(html.div(
 
 ## Interface / Examples
 
-### Basic DOM generation
+### Basic DOM generatio
 
 Accessing the `html` proxy with any string key returns a new node generator
 function:
@@ -89,7 +117,7 @@ text`Hello, ${html.b(user)}!`
 ## handle
 
 ```js
-import {handle} from 'skooma.js'
+import {handle} from 'skooma/state.js'
 ```
 
 Since it is common for event handlers to call `preventDefault()`, skooma

render.js

@@ -1,13 +1,19 @@
 // Keep a referee alive until a referrer is collected
 const weakReferences = new WeakMap()
+
+/** Keeps the referenced value alive until the referrer is collected
+ * @param {Object} referrer
+ * @param {Object} reference
+ */
 const untilDeathDoThemPart = (referrer, reference) => {
 	if (!weakReferences.has(referrer)) weakReferences.set(referrer, new Set())
 	weakReferences.get(referrer).add(reference)
 }
 
-// Like AbortController, but resets after each abort
+/** Like AbortController, but resets after each abort */
 class MultiAbortController {
 	#controller = new AbortController()
+	/** @return {AbortSignal} */
 	get signal() { return this.#controller.signal }
 	abort() { this.#controller.abort(); this.#controller = new AbortController() }
 }
@@ -16,287 +22,459 @@ class MultiAbortController {
 export const empty = Symbol("Explicit empty argument for Skooma")
 
 /** Converts a snake-case string to a CSS property name
-* @param {string} key
-* @return {string}
-*/
-const snakeToCSS = key => key.replace(/^[A-Z]/, a => "-"+a).replace(/[A-Z]/g, a => '-'+a.toLowerCase())
+ * @param {string} key
+ * @return {string}
+ */
+const snakeToCSS = key => key.replace(/^[A-Z]/, a => "-" + a).replace(/[A-Z]/g, a => '-' + a.toLowerCase())
+
+/** @typedef SpecialAttributeDescriptor
+ * @type {object}
+ * @property {function(Node):void} [get]
+ * @property {function(Node,any):void} [set]
+ * @property {function(Node,function(any):void):void} [subscribe]
+ * @property {function(Node):boolean} [filter]
+ */
 
 /**
-* @param {CSSStyleDeclaration} style The style property of a node
-* @param {object} rules A map of snake case property names to css values
-*/
-const insertStyles = (style, rules) => {
+ * Returns a fallback if value is fallback
+ * @param {any} value
+ * @param {any} whenUndefined
+ */
+const fallback = (value, whenUndefined) => typeof value != "undefined" ? value : whenUndefined
+
+/** @typedef {EventTarget & {value: any}} Observable */
+
+/** Cancelable event triggered when a reactive element gets replaced with something else */
+export class BeforeReplaceEvent extends Event {
+	/** @param {Element|Text} next */
+	constructor(next) {
+		super("beforereplace", { cancelable: true })
+		this.next = next
+	}
+}
+
+/** Event triggered when a reactive element was replaced */
+export class AfterReplaceEvent extends Event {
+	/** @param {Element|Text} next */
+	constructor(next) {
+		super("afterreplace")
+		this.next = next
+	}
+}
+
+/** Event triggered when a new element replaces an old one */
+export class ReplacedEvent extends Event {
+	/** @param {Element|Text} old */
+	constructor(old) {
+		super("replaced", { bubbles: true })
+		this.old = old
+	}
+}
+
+// Other utility exports
+
+/** Wraps an event handler in a function that calls preventDefault on the event
+ * @param {function(event) : event} fn
+ * @return {function(event)}
+ */
+export const handle = fn => event => { event.preventDefault(); return fn(event) }
+
+
+/** A reference to an element that follows it around through replacements */
+export class Ref {
+	/** @type {WeakMap<Text|Element,Text|Element>} */
+	static #map = new WeakMap()
+
+	/** @type {Element|Text} */
+	#element
+
+	/** @param {Element|Text} element */
+	constructor(element) {
+		this.#element = element
+	}
+
+	/** @return {Element|Text} */
+	deref() {
+		const next = Ref.newer(this.#element)
+		if (next) {
+			this.#element = next
+			return this.deref()
+		} else {
+			return this.#element
+		}
+	}
+
+	/** @param {Element|Text} element */
+	static newer(element) {
+		return this.#map.get(element)
+	}
+
+	/**
+	 * @param {Element|Text} previous
+	 * @param {Element|Text} next
+	 */
+	static replace(previous, next) {
+		if (this.newer(previous))
+			throw "Element has already been replaced with newer one"
+		this.#map.set(previous, next)
+	}
+}
+
+/** Main class doing all the rendering */
+export class Renderer {
+	static proxy() {
+		return new Proxy(new this(), {
+			/** @param {string} prop */
+			get: (renderer, prop) => /** @param {any[]} args */ (...args) => renderer.node(prop, args),
+			has: (renderer, prop) => renderer.nodeSupported(prop),
+		})
+	}
+
+	/** @param {string} name */
+	node(name, ...args) {
+		throw "Attempting to use an abstract Renderer"
+	}
+
+	/** @param {string|symbol} name */
+	nodeSupported(name) {
+		if (typeof(name) != "string") return false
+		return true
+	}
+
+	/** Turns an attribute value into a string */
+	/** @param {any} value */
+	static serialiseAttributeValue(value) {
+		if (typeof value == "string" || typeof value == "number")
+			return value
+		else if (value && "join" in value)
+			return value.join(" ")
+		else if (Object.getPrototypeOf(value) == Object.prototype)
+			return JSON.stringify(value)
+		else
+			return value.toString()
+	}
+}
+
+export class DomRenderer extends Renderer {
+	/** @type {Object<string,SpecialAttributeDescriptor>} */
+	static specialAttributes = Object.freeze({})
+
+	/** Processes a list of arguments for an HTML Node
+	 * @param {Element|ShadowRoot} element
+	 * @param {Array} args
+	 */
+	static apply(element, ...args) {
+		for (const arg of args) if (arg !== empty) {
+			if (Array.isArray(arg)) {
+				this.apply(element, ...arg)
+			} else {
+				const child = this.toElement(arg)
+				if (child)
+					element.append(child)
+				else if (typeof arg == "function")
+					this.apply(element, arg(element) || empty)
+				else if (arg instanceof DocumentFragment)
+					element.append(arg)
+				else if (arg && typeof(arg)=="object")
+					for (const key in arg)
+						if (element instanceof Element)
+							this.setAttribute(element, key, arg[key])
+						else
+							throw `Attempting to set attributes on a non-element (${element.constructor.name})`
+				else
+					console.warn(`An argument of type ${typeof arg} has been ignored`, element)
+			}
+		}
+	}
+
+	/** Creates a new node
+	 * @param {String} name
+	 * @param {Array} args
+	 */
+	node(name, args) {
+		const element = this.createElement(name)
+		this.constructor.apply(element, args)
+		return element
+	}
+
+	/**
+	 * @protected
+	 * @param {String} name
+	 * @param {Object} options
+	 * @return {Node}
+	 */
+	createElement(name, options={}) {
+		return document.createElement(name, options)
+	}
+
+	/** Turns an argument into something that can be inserted as a child into a DOM node
+	 * @protected
+	 * @param {any} value
+	 * @return {Element|Text}
+	 */
+	static toElement(value) {
+		if (typeof value == "string" || typeof value == "number")
+			return document.createTextNode(value.toString())
+		else if (value instanceof Element)
+			return value
+		else if (this.isObservable(value))
+			return this.toReactiveElement(value)
+	}
+
+	/**
+	 * @protected
+	 * @param {Observable} observable
+	 * @return {Element|Text}
+	 */
+	static toReactiveElement(observable) {
+		if (observable.value instanceof DocumentFragment) {
+			throw "Failed to create reactive element: Document fragments cannot be replaced dynamically"
+		}
+		const element = this.toElement(observable.value)
+		untilDeathDoThemPart(element, observable)
+		let ref = new WeakRef(element)
+
+		const handleChange = () => {
+			const element = ref.deref()
+
+			if (!element) return
+
+			const next = this.toElement(observable.value)
+			if (element?.dispatchEvent(new BeforeReplaceEvent(next))) {
+				element.replaceWith(next)
+				Ref.replace(element, next)
+				next.dispatchEvent(new ReplacedEvent(element))
+				element.dispatchEvent(new AfterReplaceEvent(next))
+				ref = new WeakRef(next)
+			}
+			observable.addEventListener("change", handleChange, {once: true})
+		}
+		observable.addEventListener("change", handleChange, {once: true})
+
+		return element
+	}
+
+	/** Set an attribute on an element
+	 * @protected
+	 * @param {Element} element
+	 * @param {string} attribute
+	 * @param {any} value
+	 * @param {AbortSignal} [cleanupSignal]
+	 */
+	static setAttribute(element, attribute, value, cleanupSignal) {
+		const special = this.getSpecialAttribute(element, attribute)
+
+		if (this.isObservable(value))
+			this.setReactiveAttribute(element, attribute, value)
+		else if (typeof value === "function")
+			element.addEventListener(attribute, value, { signal: cleanupSignal })
+		else if (special?.set)
+			special.set(element, value)
+		else if (value === true)
+			{ if (!element.hasAttribute(attribute)) element.setAttribute(attribute, '') }
+		else if (value === false)
+			element.removeAttribute(attribute)
+		else {
+			element.setAttribute(attribute, this.serialiseAttributeValue(value))
+		}
+	}
+
+	/** Set up a binding between an attribute and an observable
+	 * @protected
+	 * @param {Element} element
+	 * @param {string} attribute
+	 * @param {Observable} observable
+	 */
+	static setReactiveAttribute(element, attribute, observable) {
+		const multiAbort = new MultiAbortController()
+
+		observable.addEventListener("change", () => {
+			multiAbort.abort()
+			this.setAttribute(element, attribute, observable.value, multiAbort.signal)
+		})
+		this.setAttribute(element, attribute, observable.value, multiAbort.signal)
+
+		const special = this.getSpecialAttribute(element, attribute)
+
+		if (special?.subscribe) {
+			untilDeathDoThemPart(element, observable)
+			special.subscribe(element, value => {
+				if (value != observable.value) observable.value = value
+			})
+		}
+	}
+
+	/**
+	 * @param {CSSStyleDeclaration} style The style property of a node
+	 * @param {object} rules A map of snake case property names to css values
+	 */
+	static insertStyles(style, rules) {
 		for (const [key, value] of Object.entries(rules))
 			if (typeof value == "undefined")
 				style.removeProperty(snakeToCSS(key))
 			else
 				style.setProperty(snakeToCSS(key), value.toString())
+	}
+
+	/** Returns whether an object is an observable according to skooma's contract
+	 * @param {any} object
+	 * @return {object is Observable}
+	 */
+	static isObservable(object) {
+		return object && object.observable
+	}
+
+	/** Wraps a list of elements in a document fragment
+	 * @param {Array<Element|String>} elements
+	 */
+	static documentFragment(...elements) {
+		const fragment = new DocumentFragment()
+		for (const element of elements)
+			fragment.append(this.toElement(element))
+		return fragment
+	}
+
+	/**
+	 * @protected
+	 * @param {Element} element
+	 * @param {String} attribute
+	 */
+	static getSpecialAttribute(element, attribute) {
+		const special = this.specialAttributes[attribute]
+		if (special?.filter == undefined)
+			return special
+		if (special.filter(element))
+			return special
+		return undefined
+	}
+
+	/**
+	 * @param {String|Array<String>} data
+	 * @param {Array<String|Element>} items
+	 */
+	static createTextOrFragment(data = "", ...items) {
+		return Array.isArray(data)
+			? this.textFromTemplate(data, items)
+			: document.createTextNode(data)
+	}
+
+	/** Turns a template literal into document fragment.
+	 * Strings are returned as text nodes.
+	 * Elements are inserted in between.
+	 * @param {Array<String>} literals
+	 * @param {Array<any>} items
+	 * @return {DocumentFragment}
+	 */
+	static textFromTemplate(literals, items) {
+		const fragment = new DocumentFragment()
+		for (const key in items) {
+			fragment.append(document.createTextNode(literals[key]))
+			fragment.append(this.toElement(items[key]))
+		}
+		fragment.append(document.createTextNode(literals[literals.length - 1]))
+		return fragment
+	}
 }
 
-/** @typedef SpecialAttributeDescriptor
-* @type {object}
-* @property {function(this:any):void} [get]
-* @property {function(this:any,any):void} [set]
-* @property {function(this:any,function():void):void} [hook]
-*/
+/** Renderer for normal HTML nodes targetting a browser's DOM */
+export class DomHtmlRenderer extends DomRenderer {
+	/**
+	 * @param {String} name
+	 * @param {Object} options
+	 * @return {Node}
+	 */
+	createElement(name, options) {
+		return document.createElement(name.replace(/([a-z])([A-Z])/g, "$1-$2"), options)
+	}
 
-/**
-* @type {Object<string,SpecialAttributeDescriptor>}
-*/
-const specialAttributes = {
+	/** Creates a new node and make it a custom element if necessary
+	 * @param {String} name
+	 * @param {Array} args
+	 */
+	node(name, args) {
+		const custom = this.getCustom(args)
+		const opts = custom && { is: String(custom) }
+
+		const element = this.createElement(name, opts)
+		this.constructor.apply(element, args)
+		return element
+	}
+
+	/** Recursively finds the last 'is' attribute in a list nested array of objects
+	 * @param {Array} args
+	 */
+	getCustom(args) {
+		return args.reduce(
+			(current, argument) => Array.isArray(argument)
+				? fallback(this.getCustom(argument), current)
+				: (argument && typeof argument == "object")
+					? fallback(argument.is, current)
+					: current
+			, undefined
+		)
+	}
+
+	/** @type {Object<string,SpecialAttributeDescriptor>} */
+	static specialAttributes = {
 		value: {
-		get() { return this.value },
-		set(value) {
-			this.setAttribute("value", value)
-			this.value = value
+			/** @param {HTMLInputElement} element */
+			get(element) { return element.value },
+			/** @param {HTMLInputElement} element */
+			set(element, value) {
+				element.setAttribute("value", value)
+				element.value = value
 			},
-		hook(callback) { this.addEventListener("input", callback) }
+			/** @param {HTMLInputElement} element */
+			subscribe(element, callback) {
+				element.addEventListener("input", () => {
+					callback(this.get(element))
+				})
+			},
+			/** @param {HTMLElement} element */
+			filter(element) {
+				return element.nodeName.toLowerCase() == "input"
+			}
 		},
 		style: {
-		set(value) { insertStyles(this.style, value) }
+			/** @param {HTMLElement} element */
+			set(element, value) { DomRenderer.insertStyles(element.style, value) }
 		},
 		dataset: {
-		set(value) {
+			/** @param {HTMLElement} element */
+			set(element, value) {
 				for (const [attribute2, value2] of Object.entries(value)) {
-				this.dataset[attribute2] = processAttribute(value2)
+					element.dataset[attribute2] = DomRenderer.serialiseAttributeValue(value2)
 				}
 			}
 		},
 		shadowRoot: {
-		set(value) {
-			processArgs((this.shadowRoot || this.attachShadow({mode: "open"})), value)
+			/** @param {HTMLElement} element */
+			set(element, value) {
+				DomRenderer.apply(
+					(element.shadowRoot || element.attachShadow({ mode: "open" })),
+					value
+				)
+			}
 		}
 	}
 }
 
-const processAttribute = attribute => {
-	if (typeof attribute == "string" || typeof attribute == "number")
-		return attribute
-	else if (attribute && "join" in attribute)
-		return attribute.join(" ")
-	else
-		return JSON.stringify(attribute)
-}
-
-/** Returns a fallback if value is defined */
-const defined = (value, fallback) => typeof value != "undefined" ? value : fallback
-
-/** Recursively finds the last 'is' attribute in a list nested array of objects
-* @param {Array} args
-*/
-const getCustom = args => args.reduce(
-	(current, argument) => Array.isArray(argument)
-		? defined(getCustom(argument), current)
-		: (argument && typeof argument == "object")
-		? defined(argument.is, current)
-		: current
-	,undefined
-)
-
-/**
-* @typedef Observable
-* @type {EventTarget|object}
-* @property {any} value
-*/
-
-/** Returns whether an object is an observable according to skooma's contract
-* @param {any} object
-* @return {object is Observable}
-*/
-export const isObservable = object => object && object.observable
-
-/** Turns an argument into something that can be inserted as a child into a DOM node
-* @param {any} value
-* @return {Element|Text}
-*/
-const toElement = value => {
-	if (typeof value == "string" || typeof value == "number")
-		return document.createTextNode(value.toString())
-	else if (value instanceof Element)
-		return value
-	else if (isObservable(value))
-		return reactiveElement(value)
-}
-
-class ReplaceEvent extends Event {
-	/** @param {Element|Text} next */
-	constructor(next) {
-		super("replace", {bubbles: true, cancelable: true})
-		this.next = next
+/** Renderer for normal SVG nodes targetting a browser's DOM */
+export class DomSvgRenderer extends DomRenderer {
+	/**
+	 * @param {String} name
+	 * @param {Object} options
+	 * @return {Node}
+	 */
+	createElement(name, options) {
+		return document.createElementNS("http://www.w3.org/2000/svg", name, options)
 	}
 }
 
-class ReplacedEvent extends Event {
-	/** @param {Element|Text} next */
-	constructor(next) {
-		super("replaced")
-		this.next = next
-	}
-}
+export const html = DomHtmlRenderer.proxy()
+export const svg = DomSvgRenderer.proxy()
 
-/** @type {WeakMap<Text|Element,Text|Element>} */
-export const newer = new WeakMap()
+export const fragment = DomRenderer.documentFragment.bind(DomRenderer)
+export const text = DomRenderer.createTextOrFragment.bind(DomRenderer)
 
-/**
-* @param {Observable} observable
-* @return {Element|Text}
-*/
-export const reactiveElement = observable => {
-	const element = toElement(observable.value)
-	untilDeathDoThemPart(element, observable)
-	const ref = new WeakRef(element)
-	observable.addEventListener("change", () => {
-		const next = reactiveElement(observable)
-		const element = ref.deref()
-		if (element.dispatchEvent(new ReplaceEvent(next)))
-			element.replaceWith(next)
-		newer.set(this, next)
-		element.dispatchEvent(new ReplacedEvent(next))
-	}, {once: true})
-	return element
-}
-
-/** Set an attribute on an element
-* @param {Element} element
-* @param {string} attribute
-* @param {any} value
-* @param {AbortSignal} [cleanupSignal]
-*/
-const setAttribute = (element, attribute, value, cleanupSignal) => {
-	const special = specialAttributes[attribute]
-	if (isObservable(value))
-		setReactiveAttribute(element, attribute, value)
-	else if (typeof value === "function")
-		element.addEventListener(attribute, value, {signal: cleanupSignal})
-	else if (special?.set)
-		special.set.call(element, value)
-	else if (value === true)
-		{if (!element.hasAttribute(attribute)) element.setAttribute(attribute, '')}
-	else if (value === false)
-		element.removeAttribute(attribute)
-	else {
-		element.setAttribute(attribute, processAttribute(value))
-	}
-}
-
-/** Set up a binding between an attribute and an observable
-* @param {Element} element
-* @param {string} attribute
-* @param {Observable} observable
-*/
-const setReactiveAttribute = (element, attribute, observable) => {
-	const multiAbort = new MultiAbortController()
-
-	observable.addEventListener("change", () => {
-		multiAbort.abort()
-		setAttribute(element, attribute, observable.value, multiAbort.signal)
-	})
-	setAttribute(element, attribute, observable.value, multiAbort.signal)
-
-	const special = specialAttributes[attribute]
-	if (special.hook) {
-		untilDeathDoThemPart(element, observable)
-		special.hook.call(element, () => {
-			const current = special.get.call(element, attribute)
-			if (current != observable.value) observable.value = current
-		})
-	}
-}
-
-/** Processes a list of arguments for an HTML Node
-* @param {Element} element
-* @param {Array} args
-*/
-const processArgs = (element, ...args) => {
-	for (const arg of args) if (arg !== empty) {
-		if (Array.isArray(arg)) {
-			processArgs(element, ...arg)
-		} else {
-			const child = toElement(arg)
-			if (child)
-				element.append(child)
-			else if (arg === undefined || arg == null)
-				console.warn(`An argument of type ${typeof arg} has been ignored`, element)
-			else if (typeof arg == "function" && arg.length == 0)
-				processArgs(element, arg())
-			else if (typeof arg == "function")
-				arg(element)
-			else
-				for (const key in arg)
-					setAttribute(element, key, arg[key])
-		}
-	}
-}
-
-/** Creates a new node
-* @param {String} name
-* @param {Array} args
-* @param {Object} options
-*/
-const node = (name, args, options) => {
-	let element
-	const custom = getCustom(args)
-	const opts = custom && {is: String(custom)}
-
-	if ("nameFilter" in options) name = options.nameFilter(name)
-	if (options.xmlns)
-		element = document.createElementNS(options.xmlns, name, opts)
-	else
-		element = document.createElement(name, opts)
-	processArgs(element, args)
-	return element
-}
-
-const nameSpacedProxy = (options={}) => new Proxy(Window, {
-	/** @param {string} prop */
-	get: (_target, prop, _receiver) => { return (...args) => node(prop, args, options) },
-	has: (_target, _prop) => true,
-})
-
-export const html = nameSpacedProxy({nameFilter: name => name.replace(/([a-z])([A-Z])/g, "$1-$2").toLowerCase()})
-export const svg = nameSpacedProxy({xmlns: "http://www.w3.org/2000/svg"})
 export default html
-
-// Other utility exports
-
-/** Wraps an event handler in a function that calls preventDefault on the event
-* @param {function(event) : event} fn
-* @return {function(event)}
-*/
-export const handle = fn => event => { event.preventDefault(); return fn(event) }
-
-/** Wraps a list of elements in a document fragment
-* @param {Array<Element|String>} elements
-*/
-export const fragment = (...elements) => {
-	const fragment = new DocumentFragment()
-	for (const element of elements)
-		fragment.append(toElement(element))
-	return fragment
-}
-
-/** Turns a template literal into document fragment.
-* Strings are returned as text nodes.
-* Elements are inserted in between.
-* @param {Array<String>} literals
-* @param {Array<any>} items
-* @return {DocumentFragment}
-*/
-const textFromTemplate = (literals, items) => {
-	const fragment = new DocumentFragment()
-	for (const key in items) {
-		fragment.append(document.createTextNode(literals[key]))
-		fragment.append(toElement(items[key]))
-	}
-	fragment.append(document.createTextNode(literals[literals.length-1]))
-	return fragment
-}
-
-/**
-* @param {String|Array<String>} data
-* @param {Array<String|Element>} items
-*/
-export const text = (data="", ...items) =>
-	Array.isArray(data)
-		? textFromTemplate(data, items)
-		: document.createTextNode(data)