HTML form won't submit (Angular)

 It turns out if you mix normal HTML forms with Angular ones (i.e. using FormsModule) Angular will disable the default behaviour of forms on submit (so no POST request). To override this all you need to do is add a ngNoForm tag to the form you want to have the normal behaviour.

Why won't my Angular app include cookies in a POST request?

 Recently while working on an Angular web app operating with CORS on localhost against a SpringBoot server I had an issue where my GET requests were fine, but the POST requests (in this case for logout) did not include a cookie. At first I though I had some kind of problem with my CORS config - but this was fine:

        var corsConfig = new CorsConfiguration();
        corsConfig.setAllowedOriginPatterns(List.of(
                "http://localhost:4200",
                "http://localhost:8080"));
        corsConfig.applyPermitDefaultValues();
        corsConfig.setAllowCredentials(true);

It turns out the signature for the POST request use by Angular is slightly different! The second argument is actually for a body. So in my case:

    return this.http.post<void>(this.logoutUrl, null, {withCredentials: true});

This might help someone who is starting to question their understanding of CORS (again)