ily.li/assets/ts/PersistentWebSocket.ts

export default class PersistentWebsocket {
    private webSocket?: WebSocket;

    public constructor(
        protected readonly url: string,
        private readonly handler: MessageHandler,
        protected readonly reconnectOnClose: boolean = true,
    ) {
    }

    public run(): void {
        const _webSocket = this.webSocket = new WebSocket(this.url);
        this.webSocket.addEventListener('open', () => {
            console.debug('Websocket connected');
        });
        this.webSocket.addEventListener('message', (e) => {
            this.handler(_webSocket, e);
        });
        this.webSocket.addEventListener('error', (e) => {
            console.error('Websocket error', e);
        });
        this.webSocket.addEventListener('close', (e) => {
            this.webSocket = undefined;
            console.debug('Websocket closed', e.code, e.reason);

            if (this.reconnectOnClose) {
                setTimeout(() => this.run(), 1000);
            }
        });
    }

    public send(data: string): void {
        if (!this.webSocket) throw new Error('WebSocket not connected');

        this.webSocket.send(data);
    }
}

export type MessageHandler = (webSocket: WebSocket, e: MessageEvent) => void;