!7

html {
  if (eq(uri, "/worker.js"))
    ret [[
      addEventListener('message', function(e) {
        var startValue = e.data, i = startValue;
        postMessage("WORKING!");
        var startTime = new Date();
        while (true) {
          i = i+1;
          if ((i % 1000000) == 0) {
            var ms = new Date()-startTime;
            var mips = ((i-startValue)/ms/1000).toFixed(2);
            postMessage("Counted to: " + i + " in " + ms + " ms ("
              + mips + " million steps/s)");
            if (ms >= 4000) {
              postMessage(["continue", i]);
              break;
            }
          }
        }
      });
    ]];
    
  ret htitle("Web Worker Test")
    + hbody(
      p("Count numbers: " + hfulltag("output", "", id := "result"))
    + p(hbutton("Restart Worker", onClick := "restart()"))
    + p(hbutton("Dummy Button"))
  + hjavascript([[
    var worker;
    
    function restart() {
      worker.terminate();
      go();
    }
    
    function go() {
      cont(0);
    }
    
    function cont(i) {
      if (typeof(Worker) === "undefined") {
        document.getElementById("result").innerHTML = "Sorry, your browser does not support Web Workers...";
        return;
      }
      document.getElementById("result").innerHTML = "Making web worker";
      worker = new Worker($LINK);
      worker.onmessage = function(event) {
        var e = event.data;
        if (typeof(e) == "object" && e[0] == 'continue') {
          worker.terminate();
          //setTimeout(function() { cont(e[1]) }, 1000);
          cont(e[1]);
        } else
          document.getElementById("result").innerHTML = event.data;
      };
      worker.postMessage(i);
    }
  ]]).replace("$LINK", jsQuote(relativeRawBotLink(programID(), "worker.js"))), onLoad := "go()");
}

Began life as a copy of #1013783