route.js: a history.pushState microrouter without the routing fluff.

route.js

// Microrouter based on history.pushState.
// All thrills, no frills.
// Usage:
//
//     var h = urlstate(callback);
//     h.push('#foo')
function urlstate(callback) {
  // Since `history.pushState` doesn't fire `popstate`, we can use this function
  // instead. Will update history state and call `callback` with currently
  // showing `url`.
  function push(fragment, title) {
    history.pushState(null, null, fragment || window.location.pathname);
    callback(document.location.href);
    if (title) document.title = title;
    return document.location.href;
  }

  // Same goes for `history.replaceState`.
  function replace(fragment, title) {
    history.replaceState(null, null, fragment || window.location.pathname);
    callback(document.location.href);
    if (title) document.title = title;
    return document.location.href;
  }

  function onpopstate() {
    // Fire callback whenever a true history change happens (e.g. user 
    // presses back button).
    callback(document.location.href);
  }

  // Call callback on initialization, since Firefox doesn't fire `popstate` on
  // window load. Safari does, however. It's assumed you're doing stateless
  // routing, so a double-hit to callback on startup shouldn't hurt.
  callback(document.location.href);

  // Bind event listener.
  window.addEventListener('popstate', onpopstate);

  return { push: push, replace: replace };
}