jQuery.localizationTool.js (or just Localization Tool) allows for a client-side l10n system to be setup, system working with translated language strings stored inside JavaScript variables.
The plugin is also smart enough to tell when LTR and RTL languages...
Works with units like px, in, cm, mm, pt, pc, vw, vh, vm, em, ex, rem, vd, smaller, larger, xx-small, x-small, small, medium, large, x-large, xx-large, %, border-thin, border-medium, border-thick, thin and thick. A demo is included with the download...