citiesVisited.js

// Description:

// Lucy loves to travel. Luckily she is a renowned computer 
// scientist and gets to travel to international conferences 
// using her department's budget.

// Each year, Society for Exciting Computer Science Research (SECSR)
// organizes several conferences around the world. 
//Lucy always picks
// one conference from that list that is hosted in a city she hasn't 
// been to before, and if that leaves her with more than one option,
//  she picks the conference that she thinks would be most relevant 
//  for her field of research.

// Write a function conferencePicker that takes in two arguments:

// citiesVisited, a list of cities that Lucy has visited before, given
// as an array of strings.
// citiesOffered, a list of cities that will host SECSR conferences
// this year, given as an array of strings. citiesOffered will already
// be ordered in terms of the relevance of the conferences for Lucy's 
// research (from the most to the least relevant).
// The function should return the city that Lucy should visit, as a
// string.

// Also note:

// You should allow for the possibility that Lucy hasn't visited any
// city before.
// SECSR organizes at least two conferences each year.
// If all of the offered conferences are hosted in cities that Lucy
// has visited before, the function should return 'No worthwhile conferences 
// this year!' (Nothing in Haskell)

// Example:

// citiesVisited = ['Mexico City','Johannesburg','Stockholm','Osaka','Saint Petersburg','London'];
// citiesOffered = ['Stockholm','Paris','Melbourne'];

// conferencePicker (citiesVisited, citiesOffered);
// // ---> 'Paris'

citiesVisited = ['Mexico City', 'Johannesburg', 'Stockholm', 'Osaka', 'Saint Petersburg', 'London'];
citiesOffered = ['Stockholm', 'Paris', 'Melbourne', 'Madrid'];

function conferencePicker(citiesVisited, citiesOffered) {
    if (citiesVisited.length === 0) {
        return citiesOffered[0];
    };

    for (var city in citiesOffered) {
        var currentCity = citiesOffered[city];
        if (citiesVisited.indexOf(currentCity) === -1) {
            return currentCity;
        };
    };

    return "No worthwhile conferences this year!";
};

console.log(conferencePicker(citiesVisited, citiesOffered)); // ---> 'Paris'