77 lines
1.9 KiB
JavaScript
77 lines
1.9 KiB
JavaScript
class ChildObserver extends MutationObserver {
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constructor() {
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super(mutations => {
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for (const mutation of mutations) {
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mutation.target.dispatchEvent(new CustomEvent("change", {detail: mutation}))
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}
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})
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}
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observe(element) {
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MutationObserver.prototype.observe.call(this, element, { childList: true })
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}
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}
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export const lense = (methods, extra) => {
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if (extra) return lense(extra)(methods)
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const traps = {
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get(target, prop) {
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if (prop === "length") {
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return target.children.length
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} else if (prop === Symbol.iterator) {
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return function*() {
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for (const child of target.children) {
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yield methods.get.call(child)
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}
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}
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} else if (prop.match?.call(prop, /^[0-9]+$/)) {
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const child = target.children[prop]
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if (child) return methods.get.call(child)
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return child
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} else {
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return Array.prototype[prop]
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}
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},
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set(target, prop, value) {
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if (prop.match?.call(prop, /^[0-9]+$/)) {
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const child = target.children[prop]
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if (child) {
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methods.set.call(child, value)
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return true
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} else {
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for (let i = target.children.length; i < Number(prop); i++) {
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target.appendChild(methods.new(undefined))
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}
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const element = methods.new(value)
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target.appendChild(element)
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if (methods.get.call(element) !== value)
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methods.set.call(element, value)
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return true
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}
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} else if (prop == "length") {
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if (value == target.children.length)
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return true
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else
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return false
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}
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},
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deleteProperty(target, prop) {
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if (prop.match?.call(prop, /^[0-9]+$/)) {
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const child = target.children[prop]
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if (child) child.remove()
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return true
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}
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},
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has(target, prop) {
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return (prop === Symbol.iterator) || (prop in target.children) || (prop in Array.prototype)
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}
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}
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return element => {
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if (!(element instanceof Element)) throw(new Error("Creating domLense on non-element"))
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return new Proxy(element, traps)
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}
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}
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export default lense
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