someModule.js

/**
 *  Somewhere in an app module, pull in the app specific translator 
 */

import t from 'util/translate'

t("Edu_bs")

// => "Bachelor's"

translate.js

/**
 *  Somewhere in your app code, pull in the translator factory
 *  along with app specific translations and create a
 *  translator specific to our app
 */

import createTranslator from 'lib/translate'
import defaults         from 'app/config/translations'

export default createTranslator(defaults)

translations.js

/**
 *  App specific translations
 */

export default {
  "Income_U_50"   : "Under $50k",
  "Income_50_100" : "$50 - 100k",
  "Income_100_O"  : "Over $100k",

  "Edu_bs" : "Bachelor's",
  "Edu_ms" : "Master's",

  "Never_married" : "Never Married",
  "Married_other" : "Married - Other",
  "Married"       : "Married",

  "Parent"    : "Parent",
  "Homeowner" : "Homeowner",
  "Renter"    : "Renter",

  "Hh_U_150"   : "Under 150k",
  "Hh_150_250" : "150 - 250k",
  "Hh_250_500" : "250 - 500k",
  "Hh_500_750" : "500 - 750k",
  "Hh_750_O"   : "Over 750k",

  "Car_alone"             : "Car - Alone",
  "Car_carpool"           : "Carpool",
  "Public_transportation" : "Public",

  "Commute_U_20": "Under 20 Min",
  "Commute_20_39": "20 - 39 Min",
  "Commute_40_O": "Over 40 Min"
}

translator.fixture.js

/**
 *  Test fixture for testing the translator factory in isolation
 *  from the app specific translations
 */

export default {
  "foo": "bar"
}

translator.js

/**
 *  Exports a function that takes a translations object and returns
 *  a function that can be used to translate strings in the provided
 *  dictionary
 */
 
export default (translations) => {
  return function translate(input) {
    if (translations.hasOwnProperty(input) === false) {
      if (process.env.NODE_ENV !== 'production') {
        console.warn(`Unknown string "${ input }" for translation.`)
      }

      return input
    }

    return translations[input]
  }
}

translator.test.js

/**
 *  A test for the translator (isolated from app specific code) that ensures
 *  it translates strings within the provided translations and also that
 *  it provides a console warning if the provided string isn't found
 */

import createTranslator from '../index'
import config           from 'test/fixtures/translate'

let t = createTranslator(config)

describe('translations', function() {
  it('returns a translated string', function() {
    let result = t('foo')
    expect(result).to.equal('bar')
  })

  describe('when given an unknown string', function() {
    let message = 'Unknown string "not found" for translation.'
    let spy     = sinon.spy()
    let stub    = sinon.stub(console, 'warn', spy)

    it('returns the original string and warns the developer', function() {
      let result = t('not found')
      expect(spy.calledWith(message))
      expect(result).to.equal('not found')
    })
  })
})