Upgrade to Angular 16 break Sharepoint Ads in : this._history.replaceState is not a function

Question

I was upgrading my angular apps which run inside the Share Point office adds in. Currently angular app is using version 14, after I upgrade to angular 15 it works fine. But as soon as I upgrade to 16, I get below error.

TypeError: this._history.replaceState is not a function

This happens when calling

 this.router.navigate(['/path_to_component']);

I found a fix on this SO post. Office.js nullifies browser history functions breaking history usage

<script type="text/javascript">
    // Office js deletes window.history.pushState and window.history.replaceState. Cache them and restore them
    window._historyCache = {
        replaceState: window.history.replaceState,
        pushState: window.history.pushState
    };
</script>

<script type="text/javascript" src="https://appsforoffice.microsoft.com/lib/1/hosted/office.js"></script>

<script type="text/javascript">
    // Office js deletes window.history.pushState and window.history.replaceState. Restore them
    window.history.replaceState = window._historyCache.replaceState;
    window.history.pushState = window._historyCache.pushState;
</script>

I am not sure how this is breaking only after upgrade to Angular 16 though its relate to office.js

I am using the same version of office.js.

I have already use hash location strategy. Could any one help me to understand this.

Answer 1

Looking at Angular 14/15's source code, we can see that BrowserPlatformLocation contains this method:

override replaceState(state: any, title: string, url: string): void {
    if (supportsState()) {
      this._history.replaceState(state, title, url);
    } else {
      this.location.hash = url;
    }
  }

Sources:

1. https://github.com/angular/angular/blob/14.0.x/packages/common/src/location/platform_location.ts#L180C3-L186C4 (Angular 14)
2. https://github.com/angular/angular/blob/15.0.x/packages/common/src/location/platform_location.ts#L180C3-L186C4 (Angular 15)

What you should notice is supportsState():

export function supportsState(): boolean {
  return !!window.history.pushState;
}

In Angular 14/15 there's a fallback case if pushState is not available, so you code works well and also this._history.replaceState() works correctly.

From Angular 16, that check was removed:

override replaceState(state: any, title: string, url: string): void {
    this._history.replaceState(state, title, url);
}

Source: https://github.com/angular/angular/blob/16.0.x/packages/common/src/location/platform_location.ts#L165

So, because office.js removes pushState and replaceState and there's no fallback case, your code breaks (until you use the fix you already found).