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render.js
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@ -1,13 +1,19 @@
// Keep a referee alive until a referrer is collected // Keep a referee alive until a referrer is collected
const weakReferences = new WeakMap() const weakReferences = new WeakMap()
/** Keeps the referenced value alive until the referrer is collected
* @param {Object} referrer
* @param {Object} reference
*/
const untilDeathDoThemPart = (referrer, reference) => { const untilDeathDoThemPart = (referrer, reference) => {
if (!weakReferences.has(referrer)) weakReferences.set(referrer, new Set()) if (!weakReferences.has(referrer)) weakReferences.set(referrer, new Set())
weakReferences.get(referrer).add(reference) weakReferences.get(referrer).add(reference)
} }
// Like AbortController, but resets after each abort /** Like AbortController, but resets after each abort */
class MultiAbortController { class MultiAbortController {
#controller = new AbortController() #controller = new AbortController()
/** @return {AbortSignal} */
get signal() { return this.#controller.signal } get signal() { return this.#controller.signal }
abort() { this.#controller.abort(); this.#controller = new AbortController() } abort() { this.#controller.abort(); this.#controller = new AbortController() }
} }
@ -16,287 +22,454 @@ class MultiAbortController {
export const empty = Symbol("Explicit empty argument for Skooma") export const empty = Symbol("Explicit empty argument for Skooma")
/** Converts a snake-case string to a CSS property name /** Converts a snake-case string to a CSS property name
* @param {string} key * @param {string} key
* @return {string} * @return {string}
*/ */
const snakeToCSS = key => key.replace(/^[A-Z]/, a => "-"+a).replace(/[A-Z]/g, a => '-'+a.toLowerCase()) const snakeToCSS = key => key.replace(/^[A-Z]/, a => "-" + a).replace(/[A-Z]/g, a => '-' + a.toLowerCase())
/**
* @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) => {
for (const [key, value] of Object.entries(rules))
if (typeof value == "undefined")
style.removeProperty(snakeToCSS(key))
else
style.setProperty(snakeToCSS(key), value.toString())
}
/** @typedef SpecialAttributeDescriptor /** @typedef SpecialAttributeDescriptor
* @type {object} * @type {object}
* @property {function(this:any):void} [get] * @property {function(Node):void} [get]
* @property {function(this:any,any):void} [set] * @property {function(Node,any):void} [set]
* @property {function(this:any,function():void):void} [hook] * @property {function(Node,function(any):void):void} [subscribe]
*/ * @property {function(Node):boolean} [filter]
*/
/** /**
* @type {Object<string,SpecialAttributeDescriptor>} * Returns a fallback if value is fallback
*/ * @param {any} value
const specialAttributes = { * @param {any} whenUndefined
value: { */
get() { return this.value }, const fallback = (value, whenUndefined) => typeof value != "undefined" ? value : whenUndefined
set(value) {
this.setAttribute("value", value)
this.value = value
},
hook(callback) { this.addEventListener("input", callback) }
},
style: {
set(value) { insertStyles(this.style, value) }
},
dataset: {
set(value) {
for (const [attribute2, value2] of Object.entries(value)) {
this.dataset[attribute2] = processAttribute(value2)
}
}
},
shadowRoot: {
set(value) {
processArgs((this.shadowRoot || this.attachShadow({mode: "open"})), value)
}
}
}
const processAttribute = attribute => { /** @typedef {EventTarget & {value: any}} Observable */
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 */ /** Cancelable event triggered when a reactive element gets replaced with something else */
const defined = (value, fallback) => typeof value != "undefined" ? value : fallback export class BeforeReplaceEvent extends Event {
/** 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 */ /** @param {Element|Text} next */
constructor(next) { constructor(next) {
super("replace", {bubbles: true, cancelable: true}) super("beforereplace", { cancelable: true })
this.next = next this.next = next
} }
} }
class ReplacedEvent extends Event { /** Event triggered when a reactive element was replaced */
export class AfterReplaceEvent extends Event {
/** @param {Element|Text} next */ /** @param {Element|Text} next */
constructor(next) { constructor(next) {
super("replaced") super("afterreplace")
this.next = next this.next = next
} }
} }
/** @type {WeakMap<Text|Element,Text|Element>} */ /** Event triggered when a new element replaces an old one */
export const newer = new WeakMap() export class ReplacedEvent extends Event {
/** @param {Element|Text} old */
/** constructor(old) {
* @param {Observable} observable super("replaced", { bubbles: true })
* @return {Element|Text} this.old = old
*/
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 // Other utility exports
/** Wraps an event handler in a function that calls preventDefault on the event /** Wraps an event handler in a function that calls preventDefault on the event
* @param {function(event) : event} fn * @param {function(event) : event} fn
* @return {function(event)} * @return {function(event)}
*/ */
export const handle = fn => event => { event.preventDefault(); return fn(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. /** A reference to an element that follows it around through replacements */
* Strings are returned as text nodes. export class Ref {
* Elements are inserted in between. /** @type {WeakMap<Text|Element,Text|Element>} */
* @param {Array<String>} literals static #map = new WeakMap()
* @param {Array<any>} items
* @return {DocumentFragment} /** @type {Element|Text} */
*/ #element
const textFromTemplate = (literals, items) => {
const fragment = new DocumentFragment() /** @param {Element|Text} element */
for (const key in items) { constructor(element) {
fragment.append(document.createTextNode(literals[key])) this.#element = element
fragment.append(toElement(items[key])) }
/** @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)
} }
fragment.append(document.createTextNode(literals[literals.length-1]))
return fragment
} }
/** /** Main class doing all the rendering */
* @param {String|Array<String>} data export class Renderer {
* @param {Array<String|Element>} items static proxy() {
*/ return new Proxy(new this(), {
export const text = (data="", ...items) => /** @param {string} prop */
Array.isArray(data) get: (renderer, prop) => /** @param {any[]} args */ (...args) => renderer.node(prop, args),
? textFromTemplate(data, items) has: (renderer, prop) => renderer.nodeSupported(prop),
: document.createTextNode(data) })
}
/** @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 && 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) {
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
}
}
/** 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)
}
/** 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: {
/** @param {HTMLInputElement} element */
get(element) { return element.value },
/** @param {HTMLInputElement} element */
set(element, value) {
element.setAttribute("value", value)
element.value = value
},
/** @param {HTMLInputElement} element */
subscribe(element, callback) {
element.addEventListener("input", () => {
callback(this.get(element))
})
},
/** @param {HTMLElement} element */
filter(element) {
return element.nodeName.toLowerCase() == "input"
}
},
style: {
/** @param {HTMLElement} element */
set(element, value) { DomRenderer.insertStyles(element.style, value) }
},
dataset: {
/** @param {HTMLElement} element */
set(element, value) {
for (const [attribute2, value2] of Object.entries(value)) {
element.dataset[attribute2] = DomRenderer.serialiseAttributeValue(value2)
}
}
},
shadowRoot: {
/** @param {HTMLElement} element */
set(element, value) {
DomRenderer.apply(
(element.shadowRoot || element.attachShadow({ mode: "open" })),
value
)
}
}
}
}
/** 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)
}
}
export const html = DomHtmlRenderer.proxy()
export const svg = DomSvgRenderer.proxy()
export const fragment = DomRenderer.documentFragment.bind(DomRenderer)
export const text = DomRenderer.createTextOrFragment.bind(DomRenderer)
export default html