sS hInitSecondaryWebSocket(O... _) {
  optPar S wsVar = "ws2";
  optPar S url;
  if (empty(url)) fail("Need URL for secondary websocket"); 
  optPar S onOpen;
  optPar S onMessage;
  optPar S readyMsg = "WebSocket 2 ready!";
  ret hreconnectingWebSockets()
    + hscript([[
      var ws2Ready = false;
      var ws2InitialMsgs = [];
      var ws2Verbose = false;
      var ]] + wsVar + [[ = new ReconnectingWebSocket(]] + jsQuote(url) + [[);
      
      ]] + wsVar + [[.onopen = function(event) {
        ws2Ready = true;
        console.log(]] + jsQuote(readyMsg) + [[);
        ws2InitialMsgs.forEach(function(msg) {
          if (ws2Verbose) console.log("Sending initial msg to websocket 2: " + msg);
          ws2.send(msg);
        });
        ]] + jsDropTrailingComments(onOpen) + [[ };
        
      ]] + wsVar + [[.onmessage = function(event) {
        ]] + unnull(onMessage) + [[
      };
      
      // add an initial message to send when websocket opens
      // also send it now if ws is open already
      function ws2InitialMsg(msg) {
        ws2InitialMsgs.push(msg);
        if (ws2Ready) {
          if (ws2Verbose) console.log("Sending initial msg to websocket 2: " + msg);
          ws2.send(msg);
        }
      }
    ]]);
}

Began life as a copy of #1029959