update initial router url when running inside iframe / object tags

I'm currently rendering Vue apps inside object tags (iframe could work too) of a container/master Vue app. First I setup a fileserver serving that container or the requested sub-app to render inside the div.

For the sake of simplicity I will only show the required routing of my Node/Express server

// serve the sub-app on demand
router.get('/subApps/:appName', function(req, res) {
    res.sendFile(path.resolve(__dirname, `../apps/${req.params.appName}/index.html`);

// always render the app container if no sub-app was requested
router.get('*', function(req, res) {
    res.sendFile(path.resolve(__dirname, '../base/index.html'));

My app container / master Vue app is inside the view file rendered on /apps/:appName, requests that sub-app and wraps it into object tags

  document.getElementById("customAppContainer").innerHTML = `<object style="width: 100%; height:100%;" data="http://localhost:3000/subApps/${appKey}"></object>`;

This approach works fine but the rendered sub-app uses the startup url http://localhost:3000/subApps/app-one although it should use the url http://localhost:3000/apps/app-one. When the sub-app loads the router instance I have to change the startup url from the iframe url to the browser url (parent).

I thought about fixing that with history.replaceState

const router = new Router({ ... });

router.afterEach((to, from) => {
    localStorage.subAppRouteUpdate = to.path;

if (window.location !== window.parent.location) {
    const browserUrl = top.location.href;
    history.replaceState(null, null, browserUrl);

export default router;

Why do I want to do this? The App.vue of the master app should append the sub-app route to the browser url. With this approach it's possible to update the browser url while navigating inside the sub-app. I achieve this by storing the sub-app url to the local storage and listen for local storage changes at the master app side. So the App.vue file uses this code

export default {
  created() {
    window.addEventListener("storage", () => {
      const fullRoute = this.$router.currentRoute.fullPath;
      const routeSegments = fullRoute.split("/");
      const appsIndex = routeSegments.indexOf("apps");
      const newBaseUrlSegments = routeSegments.slice(0, appsIndex + 2);
      const newBaseUrl = newBaseUrlSegments.join("/");
      const subAppRoute = localStorage.subAppRouteUpdate;
      const updatedUrl = newBaseUrl.concat(subAppRoute);
      history.replaceState(null, null, updatedUrl);

to enable a routing while using IFrames. It almost works, this is what I get

enter image description here

Unfortunately it happens that when calling / of the sub-app the browser url gets updated to


although I'm expecting


I created a repository for reproduction / testing. Does someone know what might be wrong or how to fix that url updating?


I think the error occurs because in the router.js of the subApp I'm firing this code

if (window.location !== window.parent.location) {
    const browserUrl = top.location.href;
    history.replaceState(null, null, browserUrl);

router.afterEach((to, from) => {
    console.log({ urlToAppend: to.path });
    localStorage.subAppRouteUpdate = to.path;

The replaceState function will update the IFrame url from /subApps/app-one to the correct browser url /apps/app-one. Unfortunately this will trigger the afterEach event and to.path results in /apps/app-one although it should be /.

If the url would be /apps/app-one/users/create the after each event should trigger with /users/create of course.

But I didn't figured out how to fix this first triggered event.