method allKeysForValue

This method finds all occurrences of the specified value in the dictionary and returns an array with the corresponding keys.

var aValue = "John";
var dictObj = shell.serviceManager.basics.dictionary;
dictObj.setValueForKey("John", "FirstName");
dictObj.setValueForKey("Doe", "LastName");
dictObj.setValueForKey("John", "FatherName");
dictObj.setValueForKey("John", "UncleName");
dictObj.setValueForKey("John", "BrotherName");

//get all the key names into an array object.  See array class for more information
var allKeysMatch = dictObj.allKeysForValue(aValue);