Method close

packages/engine.io-client/lib/socket.ts:841–879

* Closes the connection.

()

   * Closes the connection.
   */
  public close() {
    const close = () => {
      this._onClose("forced close");
      debug("socket closing - telling transport to close");
      this.transport.close();
    };

    const cleanupAndClose = () => {
      this.off("upgrade", cleanupAndClose);
      this.off("upgradeError", cleanupAndClose);
      close();
    };

    const waitForUpgrade = () => {
      // wait for upgrade to finish since we can't send packets while pausing a transport
      this.once("upgrade", cleanupAndClose);
      this.once("upgradeError", cleanupAndClose);
    };

    if ("opening" === this.readyState || "open" === this.readyState) {
      this.readyState = "closing";

      if (this.writeBuffer.length) {
        this.once("drain", () => {
          if (this.upgrading) {
            waitForUpgrade();
          } else {
            close();
          }
        });
      } else if (this.upgrading) {
        waitForUpgrade();
      } else {
        close();
      }
    }

    return this;
  }

  /**
   * Called upon transport error