next.js/examples/with-mobx-state-tree-typescript/components/Clock.tsx

const format = (t) => `${pad(t.getUTCHours())}:${pad(t.getUTCMinutes())}:${pad(t.getUTCSeconds())}`;
const pad = (n) => n < 10 ? `0${n}` : n;

const Clock = (props) => {
  const divStyle = {
    backgroundColor:(props.light ? "#999" : "#000"),
    color:"#82FA58",
    display:"inline-block",
    font:"50px menlo, monaco, monospace",
    padding:"15px",
  };
  return (
    <div style={divStyle}>
      {format(new Date(props.lastUpdate))}
    </div>
  );
};

export { Clock };