71 lines
2.3 KiB
JavaScript
71 lines
2.3 KiB
JavaScript
export default class extends HTMLElement {
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constructor() {
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super()
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if (this.constructor.shadow) this.attachShadow({mode: 'open'})
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let object = this
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}
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get root() {
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return this.shadowRoot || this
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}
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connectedCallback() {
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if ("onConnect" in this) this.onConnect()
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this.dispatchEvent(new Event("connected"))
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}
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disconnectedCallback() {
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if ("onDisconnect" in this) this.onDisonnect()
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this.dispatchEvent(new Event("disconnected"))
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}
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set content(content) {
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this.root.replaceChildren(content)
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}
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attributeChangedCallback(attr, old, value) {
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let name = attr.replace(/-([a-z])/, (_, l) => l.toUpperCase())
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let attribute = this.constructor.attributes[name]
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if (name+"Changed" in this)
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if (typeof(attribute.get) == "function")
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this[name+"Changed"](attribute.get.call(this, value), attribute.get.call(this, old))
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else
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this[name+"Changed"](value, old)
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}
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// Adds property/attribute mappings to the object.
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static initialise(name = this.name) {
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let attributes = this.attributes
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? [...Object.keys(this.attributes)]
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: []
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/* See HTMLElement API */
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Object.defineProperty(this, "observedAttributes", {
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get() { return attributes.map(attr => attr.replace(/[A-Z]/, u => "-"+u.toLowerCase())) }
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})
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attributes.forEach(name => {
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let attribute = this.attributes[name]
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let htmlName = name.replace(/([a-z])([A-Z])/g, "$1-$2").toLowerCase()
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let prop = {}
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/* Is there a get filter? */
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if (typeof attribute.get == "function")
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prop.get = function() { return attribute.get.call(this, this.getAttribute(htmlName)) }
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else
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prop.get = function() { return this.getAttribute(htmlName) }
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/* Is there a set filter? */
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if (typeof attribute.set == "function")
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prop.set = function(val) { return this.setAttribute(htmlName, attribute.set.call(this, val)) }
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else if (attribute.set === false)
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prop.set = function(val) { throw(`Attribute ${name} cannot be set`) }
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else
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prop.set = function(val) { this.setAttribute(htmlName, val) }
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Object.defineProperty(this.prototype, name, prop)
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})
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name = name.replace(/([a-z])([A-Z])/g, "$1-$2").toLowerCase()
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if (this.extends)
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customElements.define(name, this, { extends: this.extends })
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else
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customElements.define(name, this)
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return name
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}
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static initialize(name) { this.initialise(name) }
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}
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