polyglot.js

var Polyglot = require('node-polyglot');

var phrases = {
  x: 'foo',
  y: '%{smart_count} bar |||| %{smart_count} bars'
};

var p = new Polyglot({
  locale: 'en',
  phrases: phrases
});

console.log(p.t('x'));    //=> foo
console.log(p.t('y', 0)); //=> 0 bars
console.log(p.t('y', 1)); //=> 1 bar
console.log(p.t('y', 2)); //=> 2 bars