How to get notified about changes of the history via history.pushState?

5.5.9.1 Event definitions

The popstate event is fired in certain cases when navigating to a session history entry.

According to this, there is no reason for popstate to be fired when you use pushState. But an event such as pushstate would come in handy. Because history is a host object, you should be careful with it, but Firefox seems to be nice in this case. This code works just fine:

(function(history){
    var pushState = history.pushState;
    history.pushState = function(state) {
        if (typeof history.onpushstate == "function") {
            history.onpushstate({state: state});
        }
        // ... whatever else you want to do
        // maybe call onhashchange e.handler
        return pushState.apply(history, arguments);
    };
})(window.history);

Your jsfiddle becomes:

window.onpopstate = history.onpushstate = function(e) { ... }

You can monkey-patch window.history.replaceState in the same way.

Note: of course you can add onpushstate simply to the global object, and you can even make it handle more events via add/removeListener

I do this with simple proxy. This is an alternative to prototype

window.history.pushState = new Proxy(window.history.pushState, {
  apply: (target, thisArg, argArray) => {
    // trigger here what you need
    return target.apply(thisArg, argArray);
  },
});