Momentjs-rails wraps the Moment.js library in a rails engine for simple use with the asset pipeline provided by Rails 3.1 and higher. The gem includes the development (non-minified) source for ease of exploration. The asset pipeline will minify in production.

Moment.js is "a lightweight javascript date library for parsing, manipulating, and formatting dates." Moment.js does not modify the native Date object. Rather, it creates a wrapper for it.