I can execute the POSIX websocket proxy examples but the programs don't do anything

I want to use the emscripten posix proxy and in order to understand how to compile and what flags to use I use the Networking examples that are cited in the emscripten wiki.

However, when I compile the tcp_echo_client.cpp with the flags

s -lwebsocket.js -sPROXY_POSIX_SOCKETS=1 -sUSE_PTHREADS=1 -sPROXY_TO_PTHREAD=1 -sPOSIX_SOCKET_DEBUG

and I deploy the posix proxy and the tcp client with node, the client don't do anything. Also there isn't any output.