The Globalize.js library, previously known as jquery-global or jQuery Globalize, is relatively small, but if you only need string localization (and not date and number localization as well), then it does not offer much more than a general setup: locale (culture) object containing the property messages. It is initialized to an empty object, and you are supposed to add properties to it, corresponding to your strings to be localized. And it has the simple method Globalize.localize() that selects a localized string for a key
To implement simple string localization, you do not necessarily need any library or plugin. You could just code some simple approach like that of Globalize.js; the general code is fairly simple, much less work than defining the actual localizations for each string. On the other hand, if you have localization needs, you might just as well use Globalize.js, preparing for other kinds of localization in the future.