Function addEvent

demo/scripts/monitor.ts:122–131

(elems: EventTarget | EventTarget[], evts: string, handler: (e: Event) => void)

}

function addEvent(elems: EventTarget | EventTarget[], evts: string, handler: (e: Event) => void) {
  evts.split(/\s+/).forEach((name) => {
    ([] as EventTarget[]).concat(elems).forEach((el) => {
      el.addEventListener(name, (e) => {
        handler(e);
        shouldUpdate = true;
      });
    });
  });
}

function sliceRecord(): RecordPoint[] {
  const last = records[records.length - 1];