Method on

webui/js/websocket.js:519–576

(eventType, callback)

  }

  async on(eventType, callback) {
    if (typeof callback !== "function") {
      throw new Error("Callback must be a function");
    }

    await this.connect();

    if (!this.subscriptions.has(eventType)) {
      const isWildcard = hasWildcardPattern(eventType);
      const eventPattern = isWildcard ? compileEventPattern(eventType) : null;
      const handler = (...args) => {
        const entry = this.subscriptions.get(eventType);
        if (!entry) return;
        const currentIsWildcard = Boolean(entry.eventPattern);
        const payload = isWildcard ? args[1] : args[0];
        const incomingEventType = isWildcard ? args[0] : eventType;
        if (currentIsWildcard) {
          if (typeof incomingEventType !== "string") return;
          if (!entry.eventPattern.test(incomingEventType)) return;
        }
        let envelope;
        try {
          envelope = validateServerEnvelope(payload);
        } catch (error) {
          console.error("WebSocket envelope validation failed:", error);
          this.invokeErrorCallbacks(error);
          return;
        }

        entry.callbacks.forEach((cb) => {
          try {
            if (currentIsWildcard) {
              cb(incomingEventType, envelope);
              return;
            }
            cb(envelope);
          } catch (error) {
            console.error("WebSocket callback error:", error);
          }
        });
      };

      this.subscriptions.set(eventType, {
        eventPattern,
        handler,
        callbacks: new Set(),
      });

      if (isWildcard) {
        this.socket.onAny(handler);
      } else {
        this.socket.on(eventType, handler);
      }
    }

    const entry = this.subscriptions.get(eventType);
    entry.callbacks.add(callback);
  }