Check if a service is already installed.
Result = window.external.IsServiceInstalled(URL, Verb)
URL Required. The main document of the activity that you want to query for. Verb Required. The type of action that this activity performs. Case-insensitive.
One of the following values:
- The service is not yet installed.
- The service is installed.
- The service is installed and it is the default for its verb type.
There is no public standard that applies to this method.