Class Socket

examples/basic-websocket-client/src/index.js:38–220

function noop() {}

class Socket extends EventEmitter {
  id;
  connected = false;

  #uri;
  #opts;
  #ws;
  #pingTimeoutTimer;
  #pingTimeoutDelay;
  #sendBuffer = [];
  #reconnectTimer;
  #shouldReconnect = true;

  constructor(uri, opts) {
    super();
    this.#uri = uri;
    this.#opts = Object.assign(
      {
        path: "/socket.io/",
        reconnectionDelay: 2000,
      },
      opts
    );
    this.#open();
  }

  #open() {
    this.#ws = new WebSocket(this.#createUrl());
    this.#ws.onmessage = ({ data }) => this.#onMessage(data);
    // dummy handler for Node.js
    this.#ws.onerror = noop;
    this.#ws.onclose = () => this.#onClose("transport close");
  }

  #createUrl() {
    const uri = this.#uri.replace(/^http/, "ws");
    const queryParams = "?EIO=4&transport=websocket";
    return `${uri}${this.#opts.path}${queryParams}`;
  }

  #onMessage(data) {
    if (typeof data !== "string") {
      // TODO handle binary payloads
      return;
    }

    switch (data[0]) {
      case EIOPacketType.OPEN:
        this.#onOpen(data);
        break;

      case EIOPacketType.CLOSE:
        this.#onClose("transport close");
        break;

      case EIOPacketType.PING:
        this.#resetPingTimeout();
        this.#send(EIOPacketType.PONG);