client.js

/* eslint-env browser */
var app = document.getElementById('app');
var time = document.getElementById('time');

var timer = setInterval(updateClock, 1000);

function updateClock() {
  time.innerHTML = new Date().toString();
}

// Edit these styles to see them take effect immediately
app.style.display = 'table-cell';
app.style.width = '400px';
app.style.height = '400px';
app.style.border = '3px solid #339';
app.style.background = '#99d';
app.style.color = '#333';
app.style.textAlign = 'center';
app.style.verticalAlign = 'middle';

// Uncomment one of the following lines to see error handling
// require('unknown-module')
// } syntax-error

// Uncomment this next line to trigger a warning
// require('Assert')
// require('assert');

if (module.hot) {
  module.hot.accept();
  module.hot.dispose(function () {
    clearInterval(timer);
  });
}