Handle the dual popstate/hashchange event handlers better

[erikringsmuth]

In some browsers a hashchange also triggers a popstate. As far as I can tell there isn't a check to see if the browser will fire one or both. The temporary fix is to keep track of the previous state (URL) and not load the route if it's to the same previous state.

this.previousState = '';
this.stateChangeHandler = function() {
  if (this.previousState !== window.location.href) {
    this.previousState = window.location.href;
    this.go();
  }
}.bind(this);
window.addEventListener('popstate', this.stateChangeHandler, false);
window.addEventListener('hashchange', this.stateChangeHandler, false);

This needs a better check so that hashchangeand popstate always call router.go().

[erikringsmuth]

More specifically, in IE a hashchange doesn't trigger popstate. It looks like most other browsers do, but detecting IE isn't the best option here either.

http://stackoverflow.com/questions/23423637/ie-not-firing-popstate-when-hashchange-happens

[erikringsmuth]

Closed by https://github.com/erikringsmuth/app-router/commit/471368a44db912ad6918397d343a4b15e0f7e1fd