the name of the preference
a Promise that resolves with true if a value has been set for the user preference, else false
let prefName = "jmapcloud-ng-core-basemap"
JMap.User
.hasPreference(prefName)
.then(hasPreferenceValue => console.log(`Preference item "${prefName}" exists: ${hasPreferenceValue.toString()}`))
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