Document title & History API

history.js

var button = document.createElement('button');
button.textContent = 'Push';
document.body.appendChild(button);

var x, title;

if (!history.state) {
  x = 0;
  title = document.title;
  // Without this we can loose the initial page's title on browser navigation
  history.replaceState({x: x, title: title}, title, location.href);
} else {
  x = history.state.x;
}

button.addEventListener('click', function() {
  x++;
  title = 'Page ' + x;
  history.pushState({x: x, title: title}, title, 'page-' + x);
  // Without this we'll loose titles on push state
  document.title = title;
});

window.addEventListener('popstate', function(e) {
  if (e.state) {
    // Without this - we'll loose titles on browser navigation
    document.title = e.state.title;
    x = e.state.x;
  }
});