const fragment = document.createDocumentFragment()
const append = () => fragment.append(document.createElement('div'))
const observer = new MutationObserver()
observer.observe(frag, {
childList: true
})
append()
append()
setTimeout(append, 1000)
setTimeout(() => observer.disconnect(), 3000)
setTimeout(append, 4000)
for await (const record of observer) {
console.log(record)
}
console.log('end')
Last active
September 28, 2021 13:22
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A MutationObserver providing an iterator
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| export class MutationObserver extends globalThis.MutationObserver { | |
| #consumed = false | |
| #promises = [] | |
| #resolve = null | |
| #enqueue = record => { | |
| if (this.#resolve) { | |
| this.#resolve(record) | |
| this.#next() | |
| } | |
| } | |
| #next = () => this.#promises.push(new Promise(this.#wait)) | |
| #wait = resolve => this.#resolve = resolve | |
| constructor () { | |
| super(records => { | |
| for (const record of records) { | |
| this.#enqueue(record) | |
| } | |
| }) | |
| this.#next() | |
| } | |
| disconnect () { | |
| this.#resolve() | |
| this.#resolve = null | |
| super.disconnect() | |
| } | |
| async* getIterator () { | |
| if (this.#consumed) { | |
| throw new Error('Unable to create an additional iterator') | |
| } | |
| this.#consumed = true | |
| while (this.#resolve || this.#promises.length) { | |
| const value = await this.#promises.shift() | |
| if (value === undefined) { | |
| break | |
| } | |
| yield value | |
| } | |
| } | |
| } |
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