44 lines
1.4 KiB
JavaScript
44 lines
1.4 KiB
JavaScript
class AwaitableWebSocket extends WebSocket {
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#received = []
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#waiting = []
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#err = null
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#opened = false
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constructor(resolve, reject, url, protocols) {
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super(url, protocols)
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this.onopen = () => {
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this.#opened = true
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resolve(this)
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}
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this.onmessage = e => {
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if (this.#waiting.length) this.#waiting.shift().resolve(e.data)
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else this.#received.push(e.data)
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}
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this.onclose = e => {
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if (!this.#opened) {
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reject(new Error(`WebSocket ${this.url} failed to connect, code ${e.code}`))
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return
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}
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this.#err = e.wasClean
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? new Error(`Websocket ${this.url} closed ${e.code}`)
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: new Error(`WebSocket ${this.url} closed with error ${e.code}`)
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this.#waiting.splice(0).forEach(p => p.reject(this.#err))
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}
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}
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recv() {
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// If we have a message already received, return it immediately
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if (this.#received.length) return Promise.resolve(this.#received.shift())
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// Wait for incoming messages, if we have an error, reject immediately
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if (this.#err) return Promise.reject(this.#err)
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return new Promise((resolve, reject) => this.#waiting.push({ resolve, reject }))
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}
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}
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// Construct an async WebSocket with await aWebSocket(url)
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function aWebSocket(url, protocols) {
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return new Promise((resolve, reject) => {
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new AwaitableWebSocket(resolve, reject, url, protocols)
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})
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}
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