A basic JavaScript object is an associative array, so it can easily be used to store key/value pairs. So using JSON, you could create an object for each string to be localized like this:
var localizedStrings={
confirmMessage:{
'en/US':'Are you sure?',
'fr/FR':'Est-ce que vous ĂȘtes certain?',
...
},
...
}
Then you could get the locale version of each string like this:
var locale="en/US";
var confirm=localizedStrings['confirmMessage'][locale];