code: function () {
      this.worker = new Worker('./js/optimizer-worker.js')
      this.worker.onmessage = function (event) {
        switch (event.data.command) {
          case 'optimized':
            Optimizer.oncomplete(event.data.id, event.data.output, event.data.saved)
        }
      }
      this.worker.onerror = function (event) {
        console.error(event)
      }
    }
docs: see setOptionsFrom in settings.js