Wrap pushState and popState into a helper function that feature detects and fires callbacks http://jsbin.com/olabac/3/edit

state.js

var State = (function() {

  var supported = !!window.history;
  var enabled = true;
  var popCallbacks = [];
  var pushCallbacks = [];
  
  var initialURL = location.href;
  
  
  function triggerPopStates(state) {
    popCallbacks.forEach(function(c) {
      c(state);
    });
  }
  
  function triggerPushStates(state, title, href) {
    pushCallbacks.forEach(function(c) {
      c(state, title, href);
    });
  }
  
  if (supported) {
    
    // Initially replace a state.  This allows a popState event to fire when going back to initial state
    history.replaceState({}, document.title, window.location.href);
    
    window.addEventListener("popstate", function(e) {
      var state = e.state;
      
      if (state) {
        triggerPopStates(state);
      }
    }, false);
    
  }
  return {
    enabled: enabled,
    disable: function() {
      enabled = false;
    },
    enable: function() {
      enabled = true;
    },
    pushState: function(state, title, href) {
      if (!supported || !enabled) {
        return;
      }
      history.pushState(state, title, href);
      triggerPushStates(state, title, href);
    },
    onPopState: function(f) {
      if (!supported || !enabled) {
        return;
      }
      popCallbacks.push(f);
    },
    onPushState: function(f) {
      if (!supported || !enabled) {
        return;
      }
      pushCallbacks.push(f);
    }
  };
})();