Задание на ШРИ 2015

shri.js

/**
 * Реализация API, не изменяйте ее
 * @param {string} url
 * @param {function} callback
 */
function getData(url, callback) {
    var RESPONSES = {
        '/countries': [
            {name: 'Cameroon', continent: 'Africa'},
            {name :'Fiji Islands', continent: 'Oceania'},
            {name: 'Guatemala', continent: 'North America'},
            {name: 'Japan', continent: 'Asia'},
            {name: 'Yugoslavia', continent: 'Europe'},
            {name: 'Tanzania', continent: 'Africa'}
        ],
        '/cities': [
            {name: 'Bamenda', country: 'Cameroon'},
            {name: 'Suva', country: 'Fiji Islands'},
            {name: 'Quetzaltenango', country: 'Guatemala'},
            {name: 'Osaka', country: 'Japan'},
            {name: 'Subotica', country: 'Yugoslavia'},
            {name: 'Zanzibar', country: 'Tanzania'},
        ],
        '/populations': [
            {count: 138000, name: 'Bamenda'},
            {count: 77366, name: 'Suva'},
            {count: 90801, name: 'Quetzaltenango'},
            {count: 2595674, name: 'Osaka'},
            {count: 100386, name: 'Subotica'},
            {count: 157634, name: 'Zanzibar'}
        ]
    };

    setTimeout(function () {
        var result = RESPONSES[url];
        if (!result) {
            return callback('Unknown url');
        }

        callback(null, result);
    }, Math.round(Math.random * 1000));
}

/**
 * Ваши изменения ниже
 */

/**
 * Комментарии к коду будем писать по-английски, т.к. код могут в дальнейшем
 * обслуживать не только русскоговорящие разработчики.
 */

/**
 * The problem with original implementation was that it created new callbacks
 * in for loop, which does not create new scope in JS.
 * As a minimal viable fix without altering a lot of code, 
 * let's use IIFE to create a new scope.
 *
 * In addition to that, let's separate the logic for retriving results data 
 * into separate function with a callback that would fire once we have all the data,
 * without leaking anything to global scope.
 */

/*
 * Our custom API to fetch all data
 *
 * @param {function} Callback that fires when all responses where gathered
 */
function getCompleteData(resultsCallback) {
	var requests = ['/countries', '/cities', '/populations'];
	var responses = {};
	for (i = 0; i < 3; i++) {
		(function(){
			var request = requests[i];
			var callback = function (error, result) {
				if (!error) {
					responses[request] = result;
					var l = [];
					for (K in responses)
						l.push(K);

					if (l.length == 3) {
						resultsCallback(responses);
					}
				}
			};
			getData(request, callback);
		}());
	}
}


/**
 * Original code to calculate population of Africa
 */
function countPopulationInAfricanCities(responses) {
	var c = [], cc = [], p = 0;
	for (i = 0; i < responses['/countries'].length; i++) {
		if (responses['/countries'][i].continent === 'Africa') {
			c.push(responses['/countries'][i].name);
		}
	}

	for (i = 0; i < responses['/cities'].length; i++) {
		for (j = 0; j < c.length; j++) {
			if (responses['/cities'][i].country === c[j]) {
				cc.push(responses['/cities'][i].name);
			}
		}
	}

	for (i = 0; i < responses['/populations'].length; i++) {
		for (j = 0; j < cc.length; j++) {
			if (responses['/populations'][i].name === cc[j]) {
				p += responses['/populations'][i].count;
			}
		}
	}

	console.log('Total population in African cities: ' + p);
}

getCompleteData(countPopulationInAfricanCities);


/**
 * Prompts for country and calculates population for all cities in that country
 */
function countPopulationInGivenCountry(responses) {
	var lookupCountry = prompt("Введите название страны", "Japan");

	var p = 0;
	for (i = 0; i < responses['/cities'].length; i++) {
		if (responses['/cities'][i].country === lookupCountry) {
			for (j = 0; j < responses['/populations'].length; j++) {
				p += responses['/populations'][j].count;
			}
		}
	}

	console.log('Total population in ' + lookupCountry + ' cities: ' + p);
}

getCompleteData(countPopulationInGivenCountry);