Method compress

packages/engine.io/lib/transports/polling.ts:323–339

* Compresses data. * * @private

(data, encoding, callback)

   * @private
   */
  private compress(data, encoding, callback) {
    debug("compressing");

    const buffers = [];
    let nread = 0;

    compressionMethods[encoding](this.httpCompression)
      .on("error", callback)
      .on("data", function (chunk) {
        buffers.push(chunk);
        nread += chunk.length;
      })
      .on("end", function () {
        callback(null, Buffer.concat(buffers, nread));
      })
      .end(data);
  }

  /**
   * Closes the transport.