Function hasPreference

hasPreference(name): Promise<boolean>
JMap.User.hasPreference

Check for a user preference existence. The returned Promise resolves with true if a value has been set for the user preference, else false. Rejects on error, or if name parameter is not string or empty string, or if no user is logged in
Parameters
- name: string
  the name of the preference
Returns Promise<boolean>
a Promise that resolves with true if a value has been set for the user preference, else false
Example
```
let prefName = "jmapserver-ng-core-basemap"
JMap.User
 .hasPreference(prefName)
 .then(hasPreferenceValue => console.log(`Preference item "${prefName}" exists: ${hasPreferenceValue.toString()}`))
```