sS hSilentComputator() {
  ret hSilentComputator(hSilentComputator_defaultURI());
}

sS hSilentComputator(S wsUri) {
  ret hSilentComputator(wsUri, "");
}

sS hSilentComputator(S wsUri, S flag) {
  if (nempty(flag)) wsUri = addSlash(wsUri) + flag;
  
  ret div("Calculating", id := 'calcing)
  + hcss([[#calcing {
position: fixed;
width: 100%;
height: 100vh;
z-index: 9999;
visibility: hidden;
}]])
    + hMakeComputerID()
    + hreconnectingWebSockets()
    + hjavascript([[
      function sendPing() {
        ${PINGCMD}
      }
      
      var working = false;
      var benchResultl;
      var ws = new ReconnectingWebSocket("${URI}");
      ws.onopen = function(event) {
        console.log("WebSocket opened.");
      };
      ws.onmessage = function(event) {
        var d = event.data;
        while (d.length > 0 && d.charCodeAt(d.length-1) == 0)
          d = d.substring(0, d.length-1);
        console.log("Evaluating: " + d);
        var geval = eval; // use global scope
        geval(d);
        console.log("Evaluated.");
      };
      
      //working = true; // XXX
      //console.log("Eval test: " + eval('working'));
  ]].replace("${URI}", wsUri)
    .replace("${PINGCMD}", nodes_pingCmd()));
}

Began life as a copy of #1013835