Web worker poll request

	// this.timer.terminate();  close worker
    timerWorker() {
    
      console.log("timerWorker");
      function createWorker(f) {
    
        let blob = new Blob(["(" + f.toString() + ")()"]);
        let url = window.URL.createObjectURL(blob);
        let worker = new Worker(url);
        return worker;
      }
      this.timer = createWorker(() => {
    
        setInterval(() => {
    
          self.postMessage("timer");
        }, 1000);
      });
      this.timer.onmessage = () => {
    
        //  polling 
      };
      this.timer.postMessage("init");
    },