Multilanguage Support in Apache Cordova
Typically localization might be achieved through storing localization in configuration files (perhaps in JSON) which would be deployed along with the application. The appropriate config would be loaded into memory based on localization setting such that main app code code just references a string identifier.

This would be in contrast to your approach of loading all translations into javascript variables in memory, which could get memory intensive if you have a large number of strings. 

So you might take a look at a plug-in like this which takes this general approach.