Given a string representing a URL, returns the platform-specific external URL path.
If the given URL doesn't begin with a leading slash ('/'), this method adds one
before normalizing. This method will also add a hash if HashLocationStrategy is
used, or the APP_BASE_HREF if the PathLocationStrategy is in use.
Source
String prepareExternalUrl(String url) {
if (url.length > 0 && !url.startsWith("/")) {
url = "/" + url;
}
return this.platformStrategy.prepareExternalUrl(url);
}