next.js/examples/with-redux-reselect-recompose/components/clock.js

import React from 'react'
import PropTypes from 'prop-types'
import { compose, pure, setDisplayName, setPropTypes } from 'recompose'

const format = t =>
  `${pad(t.getUTCHours())}:${pad(t.getUTCMinutes())}:${pad(t.getUTCSeconds())}`

const pad = n => (n < 10 ? `0${n}` : n)

const Clock = ({ lastUpdate, light }) => (
  <div className={light ? 'light' : ''}>
    {format(new Date(lastUpdate))}
    <style jsx>{`
      div {
        padding: 15px;
        display: inline-block;
        color: #82fa58;
        font: 50px menlo, monaco, monospace;
        background-color: #000;
      }

      .light {
        background-color: #999;
      }
    `}</style>
  </div>
)

export default compose(
  setDisplayName('Clock'),
  setPropTypes({
    lastUpdate: PropTypes.number,
    light: PropTypes.bool
  }),
  pure
)(Clock)