Function encodeFrame

packages/socketio-shim/src/framing.ts:60–73

(packet: Packet)

 * trim trailing ones only when strictly safe (no data and no endpoint).
 */
export function encodeFrame(packet: Packet): string {
  const typePart = String(packet.type);
  const idPart = packet.id === undefined ? '' : String(packet.id);
  const endpointPart = packet.endpoint ?? '';
  const dataPart = packet.data ?? '';

  // Always emit at least `<type>:<id>:<endpoint>`. Append `:<data>` only if
  // data is present — trailing empty segment is legal but noisy, and the
  // reference parser is happy with either form.
  if (dataPart === '') {
    return `${typePart}:${idPart}:${endpointPart}`;
  }
  return `${typePart}:${idPart}:${endpointPart}:${dataPart}`;
}

/**
 * Decode a raw wire string into a Packet, or return null for anything