background.html

<h1>Background</h1>

<script type="text/javascript">
  // Send logs as messages to the main thread to show on the console
  function log(value) {
    window.api.log(value);
  }

  // let the main thread know this thread is ready to process something
  function ready() {
    window.api.ready();
  }

  // do some work that will tie up the processor for a while
  function work() {
    // see https://gist.github.com/tkrueger/3500612 for generating load
    var start = new Date().getTime();
    var result = 0;
    var finished = false;
    while (!finished) {
      result += Math.random() * Math.random();
      finished = new Date().getTime() > start + 10000;
    }
  }

  // if message is received, pass it back to the renderer via the main thread
  window.api.message((arg) => {
    log("received: " + arg);
    window.api.forRenderer(arg);
    ready();
  });

  window.api.task((arg) => {
    log("starting: " + arg);
    work();
    log("finished: " + arg);
    ready();
  });

  ready();
</script>