imperativeVSfuncProg.js

//Imperative:
//Too many if-else and null checks; relying on global indexURLs; decided that "en" urls are default for any country
const getUrlForUser = (user) => {
  if (user == null) { //not logged in
    return indexURLs['en']; //return default page
  }
  if (user.prefs.languages.primary && user.prefs.languages.primary != 'undefined') {
    if (indexURLs[user.prefs.languages.primary]) {//if translation exists,
      return indexURLs[user.prefs.languages.primary];
    } else {
      return indexURLs['en'];
    }
  }
}

//call
showIndexPage(getUrlForUser(joeUser));


//Functional Programming:
//(Little hard to understand at first but is more robust and bug free)
//FP techniques used: Functors, "Maybe Monad" and "Currying"
const R = require('ramda');
const prop = R.prop;
const path = R.path;
const curry = R.curry;
const Maybe = require('ramda-fantasy').Maybe;

const getURLForUser = (user) => {
    return Maybe(user)//wrap user in a Maybe object 
        .map(path(['prefs', 'languages', 'primary'])) //use Ramda's to grab primary language
        .chain(maybeGetUrl); //pass language to maybeGetUrl &  get url or null Monad
}

const maybeGetUrl = R.curry(function(allUrls, language) {//curry to convert this to a single arg func
    return Maybe(allUrls[language]);//return Monad(url | null)
})(indexURLs);//pass indexURLs instead of accessing globally


function boot(user, defaultURL) {
   showIndexPage(getURLForUser(user).getOrElse(defaultURL));
}

boot(joeUser, 'http://site.com/en'); //'http://site.com/sp'